UC-NRLF 


1906 


!     ^ 

^urO^ lA/Ofc 


^_ 


LIBRARY 

OF   THE 

UNIVERSITY  OF  CALIFORNIA. 

Class 


MONOGRAPHS 

ON 

APPLIED  ELECTROCHEMISTRY 

EDITED  BY 

VIKTOR  ENGELHARDT, 

Chief  Engineer  and  Chemist  of  the  Siemens  &  Halske  Co.,  Limited, 

Vienna. 

WITH  THE  COOPERATION  OF 

Dr.  E.  Abel,  Chemist  for  the  Siemens  &  Halske  Co.,  Ltd.,  Vienna. 

Dr.  P.  Askenasy,  technical  manager  of  the  Accumulator  plant,  Liesing. 

H.  Becker,  editor  of  "  L'Industrie  electro-chimique, "  Paris. 

Dr.  W.  Borchers,  Professor  at  the  Technical  High  School,  Aachen. 

Sh.  Cowper-Coles,  Editor  of  "  The  Electrochemist  and  Metallurgist, " 
London. 

Dr.  F.  Dieffenbach,  Professor  at  the  Technical   High  School,  Darm- 
stadt. 

Dr.  G.  Erlwein,  Chief    Chemist  of  the  Siemens  &  Halske  Co.,   Ltd., 
Berlin. 

H.  Friberg,  Engineer  of  the  Siemens  &  Halske  Co.,  Ltd.,  Berlin. 

H.  Gall,  Director  of  the  Socie"te"  d'Electrochimie,  Paris. 

F.  E.  Giinther,  Mining  Engineer,  Aachen. 

Dr.  F.  Haber,  Professor  at  the  Technical  High  School,  Karlsruhe. 

Dr.  C.  Haussermann,  Professor  at  the  Technical  High  School,  Stutt- 
gart. 

Dr.  R.  Hammerschmidt,  Electrochemist,  Charlottenburg. 

Dr.  G.  Hausdorff,  Official  Chemist,  Essen. 

Dr.  K.  Kellner,  General-director,  Vienna. 

A.  Krakau,  Professor  at  the  Electrotechnical  Institute,  St.  Petersburg. 

Dr.  H.  Landolt,  Director  of  the  Society  of  Electrochemical  Industry, 
Turgi. 

Dr.  M.  Le  Blanc,  Professor  at  the  Technical  High  School,  Karlsruhe. 

C.  Liebenow,   Engineer,  Berlin. 

Dr.  R.  Lorenz,  Professor  at  the  Swiss  Polytechnick,  Zurich. 

Dr.  R.  Lucion,  Director  of  Solvay  &  Co.,  Briissel. 

A.  Minet,  Editor  of  "  L'Electrochimfe,  "  Paris. 

A.  Nettel,  Engineer,  Berlin. 

H.  Nissenson,  Director  of  the  Stolberg  &  Westfalen  Co.,  Ltd.,   Stol- 
berg. 

Dr.  F.  Peters,  Instructor  at  the  Royal  Mining  Academy,  Berlin. 

Dr.  W.  Pfanhauser,  Manufacturer,  Vienna. 

Registered    Chemist  Dr.   O.  Prelinger,    Chemist  for  the  Siemens    & 
Halske  Co.,  Ltd.,  Vienna. 

Dr.  Th.  Zettel,  Chief  Chemist  of  Brown-Boveri  &  Co.,  Baden. 
And  other  experts. 


MONOGRAPHS    ON    APPLIED     ELECTROCHEMISTRY. 

VOL  I. 

THE 

ELECTROLYSIS  OF  WATER 

PROCESSES  AND  APPLICATIONS 

BY 


VIKTOR  ENGELHARDT 
rr 


CHIEF  ENGINEER  AND  CHEMIST  OF  THE  SIEMENS  &  HALSKE 
Co.,  LIMITED,  VIENNA. 


AUTHORIZED  ENGLISH  TRANSLATION  BY 

JOSEPH  W.  RICHARDS,  M.A.,  A.C.,  PH.D., 

PRESIDENT  OF  THE  AMERICAN  ELECTROCHEMICAL  SOCIETY. 
PROFESSOR  OF  METALLURGY  AT  LEHIGH  UNIVERSITY. 


With  90  Figures  and  15  Tables  in  the  Text. 

OF  THE  ^V 

UNIVERSITY  j 

EASTON,  PA.  : 

PUBLISHED  BY  THE  CHEMICAL  PUBLISHING  COMPANY. 
1904. 


COPYRIGHT,  1904,  BY  THE  CHEMICAL  PUBLISHING  Co. 


OF  THE 

'DIVERSITY 

Vor 
*£AUFOW£ 

AUTHOR'S  PREFACE  TO  GERMAN  EDITION. 

Corresponding  with  the  rapid  growth  which  the  application 
of  electrochemical  processes  have  shown  in  practice,  the 
literature  of  this  field  has  grown  remarkably  in  the  last  ten 
years  of  the  past  century.  This  literature  has,  however,  in 
spite  of  the  existence  of  present  German  and  other  treatises 
and  the  regularly  appearing  periodicals,  yet  exclusively  re- 
mained a  simple  current  report.  Those-  works  which  have 
appeared,  which  in  a  concise  form  treat  of  the  larger  field' of 
applied  electrochemistry,  are  for  the  most  part  primarily  in- 
tended for  students  and  therefore  have  a  general  character. 
Special  treatises  on  applied  electrochemistry  which  will  treat 
of  their  subjects  exhaustively  in  all  directions  are,  with  the 
very  few  exceptions,  not  in  existence. 

This  deficiency  is,  however,  easily  explainable  if  we  con- 
sider more  closely  the  way  in  which  electrochemical  processes 
reach  commercial  applications. 

We  can,  on  the  whole,  if  we  leave  out  of  consideration  the 
electrochemical  sources  of  the  current,  which  form  a  group 
of  themselves,  divide  these  electrochemical  processes  into  two 
principal  classes. 

One  series  of  processes  which  we  may  designate  as  electro- 
chemical installation-processes,  have  as  their  object,  with- 
out forming  a  branch  of  manufacture  themselves,  to  introduce 
technical  improvements  or  economies  in  the  existing  indus- 
tries and  processes. 

What  appears  on  such  processes  in  literature  is  only  in 
rarest  cases  published  by  the  industries  making  use  of  the 
processes  themselves ;  but  in  the  main  by  the  patentees  of  the 
process  in  question,  who  are  in  most  cases,  identical  with 
the  manufacturers  of  the  machinery  and  apparatus  necessary 
for  the  practice  of  the  process.  Since  it  is  in  the  interest  of 
the  latter  to  erect  as  many  plants  as  possible,  the  literature 
must  be  exploited  for  advertising  purposes.  The  description 


iv  AUTHOR'S  PREFACE. 

given  of  the  form  of  apparatus  is  usually  only  diagrammatic, 
and  often  has  the  object  of  deceiving  those  who  should  hope 
to  work  in  the  same  direction.  As  an  example  of  such  elec 
trochemical  installation  we  may  quote  the  electrolytic  puri- 
fication of  beet-sugar  solution,  the  so-called  electrical  bleach- 
ing, many  applications  of  ozone,  the  electrolytic  decomposition 
of  water,  some  metallurgical  refining  processes,  etc. 

The  second  large  group  are  the  real  electrochemical  manu- 
facturing processes  like  the  chlorine  and  alkali  industry,  the 
manufacture  of  chlorates,  carbides,  most  of  the  metallurgical 
applications  of  electrochemistry  and  the  like.  In  these  pro- 
cesses the  withholding  of  published  information  is  greater  than 
in  the  previous  ones.  With  the  exception  of  the  patent 
specifications,  very  little  is  made  public.  Every  practical 
electrochemist  knows  how  far  the  principles  described  in  the 
patent  specifications  are  different  from  the  real  applications 
in  practice. 

Iii  the  collection  of  "  Monographs  of  Applied  Electrochem- 
istry," the  first  volume  of  which  is  herewith  published,  it 
will  be  the  object  to  set  forth  detailed  and  most  authentic 
reports  in  the  field  of  applied  electrochemistry.  These  mono- 
graphs will  not  be  general  compilations  on  the  present  con- 
dition of  the  several  fields  of  applied  electrochemistry,  but 
exhaustive  special  reports,  in  which  the  entire  historical  de- 
velopment will  be  set  forth,  and  a  good  review  of  the  most 
important  patent  literature  made.  An  endeavor  will  further 
be  made  to  modify,  as  far  as  possible,  the  conservatism  of  the 
commercial  circles  and  to  give  as  far  as  possible  commercial 
data,  such  as  cost  of  plant  and  operation,  commercial  con- 
ditions and  the  like. 

Our  co-operators,  who  on  the  one  side  are  instructors  in  elec- 
trochemistry in  the  technical  colleges,  in  close  connection  with 
the  pioneers  of  electrochemistry,  on  the  other  side  practical 
electrochemists  in  successful  commercial  work,  permit  the 
hope  of  our  success  to  appear  well-founded. 

Yet  we  do  not  like  to  narrow  the  boundaries  which  we  will 


TRANSLATOR'S  PREFACE.  v 

observe  in  the  "  Monographs  of  Applied  Electrochemistry.'' 
How  much  work  which  was  undertaken  with  a  purely  theo- 
retical interest  really  provides  a  rich  source  of  valuable  mate- 
rial for  industrial  applications!  How  valuable  for  the  prac- 
tical man  would  be  the  exhaustive  reports  on  the  special  con- 
ditions of  work  and  production  in  the  different  countries  in 
which  electrochemistry  flourishes! 

We  therefore  hope  that  the  collection  of  treatises  whose 
publication  is  now  begun  will  be  a  welcome  assistance  to  our 
professional  men  in  their  work. 

Surely  we  will  reach  this  goal  if  not  only  the  above-named 
cooperators  but  all  professional  men  will  aid  us  by  commu- 
nicating their  experiences  and  reporting  any  modifications  or 
mistakes. 

For  assistance  rendered  in  this  direction  we  therefore  offer 
our  best  thanks  in  advance. 

VIKTOR  ENGELHARDT. 

Vienna,  January,  1902. 


TRANSLATOR'S    PREFACE. 

To  any  one  in  the  least  conversant  with  the  rapid  recent 
growth  of  applied,  as  well  as  theoretical  electrochemistry,  no 
apology  or  explanation  will  be  necessary  regarding  the  time- 
liness of  translating  the  present  series  of  monographs.  A 
considerable  proportion  of  the  English-speaking  electrochemists 
can  read  the  German  text,  but  a  still  larger  proportion  can- 
not, and  that  the  latter  class  may  have  access  to  the  thoughts 
and  ideas  of  these  monographs,  is  the  purpose  of  these  trans- 
lations. 

The  present  work  is  rich  in  suggestions  of  ways  and  means 
for  accomplishing  difficult  ends,  in  electrochemical  op- 
erations ;  its  perusal  will  be  found  instructive  and  stimu- 
lating to  the  electrochemist  in  any  line.  It  is  therefore  of 


vi  TRANSLATOR'S  PREFACE. 

far  greater  value  than  a  mere  code  of  operations  for  producing 
hydrogen  and  oxygen,  as  will  be  recognized  by  the  reader  as 
soon  as  he  reads  into  the  text. 

The  translator  wishes  here  to  acknowledge  his  indebted- 
ness to  W.  S.  Landis,  E.M.,  for  his  considerable  assistance  in 
taking  down  the  translation  and  reading  proof-sheets. 

JOSEPH  W.  RICHARDS. 
Metallurgical  Laboratory, 
Lehigh  University, 
Sept.  22,  1903. 


CONTENTS. 


I.  HISTORICAL  REVIEW  : 

Introduction T 

The  Discovery  of  the  Electrolytic  Decomposition  of  Water. i 

Older  Literature 4 

II.  THE  CONSTANTS  OF  THE  ELECTROLYTIC  DECOMPOSITION  OF  WATER  : 
Chemical  and  Electrochemical  Constants 6 

A .  Oxygen 6 

B.  Hydrogen 7 

C.  Detonating  Gas 7 

Decomposition  Voltage  7 

Conductivity 8 

III.  REVIEW  OF  THE  PROCESSES  : 

A.  Processes  and  Apparatus  for  the  Separate  Production  of  Oxygen 

and  Hydrogen 9 

(a)  With  Porous  Diaphragms  of  Non-conducting  Material 9 

Process  of  d'Arsonval,  1885 10 

Form  of  Apparatus    10 

Process  of  Latchinoff 1 1 

Patent  Claim n 

First  Method  of  Operation 1 1 

Later  Methods  of  Operation 12 

Drying  of  the  Gases 14 

Moderation  of  Complications 15 

Bipolar  Connections 15 

Electrolysis  under  Pressure .  15 

Plant 17 

Output  • 18 

Cost  of  Operation 18 

Practice 18 

Process  of  Ducretet,  1888 19 

Form  of  Apparatus 19 

Process  of  Renard,  1888-1890 19 

Output  -  • 20 

Form  of  Apparatus 20 

Practice 21 

Cost  of  Plant  and  Operation 21 

Laboratory  Apparatus 21 

Process  of  Delmard,  1890 23 

Process  of  Bell,   1893 24 

Patent  Claim 24 

P'orm  of  Apparatus 25 

Practice 27 


Vlll  CONTENTS. 

Process  of  Schmidt,   1899 27 

Patent  Claim 28 

Description 28 

Form  of  Apparatus 30 

Output 31 

Purity  of  the  Gases 31 

Types  of  Apparatus 32 

Arrangement 33 

Rules  for  Operating 33 

(a )  Gasometer 33 

(£)  Conductors  and  Water  Supply 34 

(c)  Measuring  and  Controlling  Apparatus 35 

(d)  Cocks  and  Joints 35 

(<?)  Gas  Pressure 35 

(/)  Burner 36 

(g)  Setting  Up  of  the  Apparatus 37 

(h)  Charging 37 

(z)    Starting  Up 37 

(k)  Operation 38 

Cost  of  Plant  for  the  Sale  of  Compressed  Gas 39 

Cost  of  Operation  for  the  Sale  of  Compressed  Gas 39 

Cost  of  Operation  without  Compression 40 

( a ]  for  Detonating  Gas 41 

(b]  for  Oxygen 41 

(c]  for  Hydrogen 42 

Practice    4? 

(b)    With  Complete  Non-conducting  Partitions 43 

( a )   For  Instruction  and  Laboratory  Apparatus 4 } 

Ritter's  Apparatus 43 

Forms  of  the  Apparatus 44 

Hofmann's  Apparatus 45 

Buff's  Apparatus 46 

Rosenfeld's  Apparatus 46 

Rebenstorff 's  Apparatus 47 

Habermann's  Apparatus 48 

(d)  For  Technical  Purposes 49 

Process  of  Ascherl,   1894 49 

Patent  Claim 49 

Description 49 

Practice 52 

Process  of  Schoop,   1900 52 

Patent  Claim 52 

Form  of  Apparatus 53 

Output 56 

•Cost  of  Operation 56 

Practice 57 


CONTENTS.  ix 

Process  of  Hazard-Flamand,  1898 58 

Form  of  Apparatus 58 

Practice 61 

Process  of  Verney,  1899 61 

Form  of  Apparatus 61 

Practice 6 1 

(c)    With  Complete  or  Perforated  Conducting  Partitions 61 

Process  of  Garuti,    1893 61 

Patent  Claim 62 

Principle 62 

Form  of  Apparatus 64 

Variation  of  the  Apparatus 67 

Operation 72 

Purity  of  the  Gases 73 

Cost  of  Operation 74 

Cost  of  Plant 76 

Practice 76 

Process  of  Siemens  Bros,  and  Obach,  1893 So 

Form  of  Apparatus 80 

Output 81 

Cost  of  Operation  and  Plant 82 

Process  of  Schuckert,  1896 83 

Patent  Claim 83 

Description 84 

Management 85 

Normal  Types 86 

Output 86 

Cost  of  Plant 87 

Cost  of  Operation 87 

Practice 88 

B.  Processes  and  Apparatus  for  the  Electrolysis  of  Water  without 

Separation  of  the  Gas  (Production  of  Detonating  Gas] 88 

(a)  For  Purposes  of  his  (ruction  and  Laboratory  Work  (  Voltameter}  88 

General 88 

Reduction  of  Gas  Volumes 89 

Connections  for  Calibration  of  Apparatus 90 

Simple  Forms  of  Apparatus   91 

Voltameter  of  Kohlrausch 91 

"  De  la  Rive 92 

' '   Bunsen 92 

"  Oettel 93 

"   Walter  Neumann 95 

"   Berlin 97 

1 '  Minet 98 

' '  Minet  for  Industrial  Purposes 100 

( b )  For  Technical  Purposes • 102 

Process  of  Eldridge,  Clarke  and  Blum,  1898 102 


X  CONTENTS. 

C.  Processes  for  the  Simple  Evolution  of  Oxygen 105 

(a)  Through  Depolarization  at  the  Cathode 105 

Process  of  Coehn,   1893 105 

Patent  Claim 105 

Description 105 

Copper  Oxide  Cathodes 106 

Process  of  Habennann,   1892 106 

( b )  By  the  Precipitation  of  Metal  at  the  Cathode 107 

Precipitation  of  Copper 107 

CHRONOLOGICAL  REVIEW 107 

IV.  APPLICATIONS: 

General no 

Cost  of  Plant no 

Cost  of  Operation 112 

Consumption  of  Anodes 112 

Absorption  of  Carbon  Dioxide 114 

Security  from  Explosions 114 

Concurrent  Processes 1 14 

1 i )  Electrochemical  Processes 1 14 

(a]  Hydrogen 114 

(b)  Oxygen 116 

( 2 )  Physical  Processes 116 

(a)  Oxygen 116 

(3)  Chemical 118 

(a)  Hydrogen 118 

(b)  Oxygen 1 18 

Compression 118 

Special  Applications 119 

1 i )  Detonating  Gas 119 

(a )  High  Temperature 119 

(b)  Lighting 120 

(c)  Blasting  Purposes 121 

( 2 )  Hydrogen 1 23 

(a)  Ballooning  Purposes 123 

(b}  Soldering  Purposes 123 

(c)  Lighting 126 

(d)  Motor  Purposes 130 

(3)  Oxygen 130 

V.  APPENDIX: 

Reduction  of  Gas  Volume  to  a  Barometric  Pressure  of  760  mm 132 

Reduction  of  Gas  Volume  to  a  Temperature  of  o°  C 133 

Tension  of  Water  Vapor  in  mm.  of  Mercury  for  Temperatures  be- 
tween —2°  C  to  -f  35°  C 135 

Conductivity  of  the  Electrolytes  Which  Are  Made  Use  Of  in  the 

Technical  Electrolysis  of  Water 137 

Index  of  Authors •  •  •  139 


UNIVERSITY    I 

OF  J 

I.     HISTORICAL  REVIEW. 

INTRODUCTION. 

Beginning  as  we  do  the  collection  of  "  Monographs  of  Ap- 
plied Electrochemistry,"  with  a  description  of  the  electroly- 
sis of  water,  this  is  not  done  under  the  assumption  that  the 
processes  included  therein  are  of  the  highest  interest  among 
present  electrochemical  questions,  from  a  technical  stand- 
point, but  out  of  the  feeling  of  thankfulness  towards  those  in- 
vestigators, who  more  than  one  hundred  years  ago  first  worked 
with  the  chemical  action  of  the  electric  current  and  first  recog- 
nized such  in  the  electrolytic  decomposition  of  water. 

THE  DISCOVERY  OF  THE  ELECTROLYTIC  DECOMPOSITION  OF 

WATER. 

Even  the  investigations  on  the  decomposition  of  combined 
bodies  by  the  electric  spark,  which  preceded  a  knowledge  of 
the  Voltaic  pile,  had  their  first  undoubted  results  in  the  de- 
composition of  water.  Pacts  van  Troostwijk  and  Deimann 
communicated  in  the  year  1789  in  a  letter  to  de  la  Metherie, 
their  observations,  according  to  which  they  had  decomposed 
water  by  the  electric  spark  into  combustible  air  and  vitalized 
air.1 

J.  W.  Ritter  in  the  year  1798  recognized  also  the  relation 
between  chemical  and  electrochemical  phenomena,  but  the 
electrolytic  action  could  not  be  further  investigated  until  a 
more  powerful  means  was  at  hand  than  the  simple  pairs  of 
metallic  plates  known  in  1800.  The  Voltaic  couple  first  gave 
to  investigators  of  that  time  the  assistance  which  was  needed.2 

As  Ostwald  says  in  his  classical  work3  the  chemical  action 
of  the  Voltaic  pile  escaped  observation  by  Volta  himself. 

1  Ostwald  :  Elektrochemie,  ihre  Geschichte  und  Lehre   1896,  21.     Ob- 
servations sur   la   physique   etc.,   35,    1789,    369-378.     Grens  Journal  der 
Physik.,  2,  1790,  130.     Kopp:  Geschichte  der  Chemie,  1845,  III,  274. 

2  Phil.  Trans.,  1800,  II,  405-431.     Ostwald:    Elektrochemie,  ihre  Ge- 
schichte und  Lehre,  1896,  115. 

3  Ostwald  :  Elektrochemie,  ihre  Geschichte  und  Lehre,  1896,  129. 


2  ELECTROLYSIS   OF   WATER. 

Ostwald  writes  about  this  :  "  The  very  evident  oxidation 
phenomenon  at  the  plates  was  wholly  left  out  of  consideration 
by  Volta ;  indeed  from  the  researches  which  he  reports  it  may 
be  seen  that  he  took  wires  from  the  end  of  his  pile  and  dipped 
them  into  water,  so  that  necessarily  electrolysis  and  evolution 
of  gas  must  have  taken  place,  but,  although  describing  with 
the  greatest  care  every  other  single  phenomenon  he  makes  no 
single  suggestion  that  he  had  seen  any  chemical  action." 

Ritter  was  indeed,  as  is  shown  by  the  investigations  of  Ost- 
wald, the  first  to  observe  decomposition  of  water  by  the  elec- 
tric current.1 

•For  a  long  time  the  priority  of  this  discovery  was  ascribed 
to  the  Englishmen  Nicholson  and  Carlisle.  Kopp2  writes 
as  follows:  u  In  the  year  1800  the  Englishmen  Nich- 
olson and  Carlisle,  in  the  course  of  investigations  made  to- 
gether, observed  that  in  discharging  the  Voltaic  pile  through 
water,  evolution  of  gas  takes  place  and  that  the  water  was  de- 
composed into  its  constituents  by  electricity,  evolving  them 
both  as  gases  as  long  as  the  conducting  wires  in  contact  with 
the  water  consisted  of  an  unoxidizable  metal.  These  are  the 
first  recognitions  of  galvanic  electricity  as  a  chemical  agent." 

Landriani  was  led  by  the  publication  of  Nicholson's3  ob- 
servations to  repeat  the  experiment,  and  it  was  through  this 
that  Volta  first  knew  of  the  phenomenon  which  had  been  dis- 
covered by  the  use  of  his  pile.  For  its  historical  interest  a 
picture  of  the  apparatus  as  used  by  Landriani  is  reproduced 
in  Fig.  i.4 

Quite  a  number  of  investigators  followed  this  line  of  inves- 
tigation. The  puzzling  appearance  of  acids  and  bases  at  the 
electrodes  coming  from  the  small  amounts  of  impurities  in 
the  water,  led  to  the  investigation  of  Davy,  and  to  the  accu- 

1  Ritter:  Beitrage  zur  Kenntnis  des  Galvanismus,  1800,  1,  252.     Voigts 
Magazin   fur  den   neuest.     Zust.   d.    Naturk,     1800,    2,    356.     E.    Hoppe  : 
Elektrotech.  Zeitschr.,  1888,  9,  36. 

2  Kopp  :  Geschichte  der  Chemie,  II,  1844,  330. 

3  Nicholson's  Journal  of  Nat.  Philos.,  1800,  4,  179. 

4  Ostwald  :  Elektrochemie,  ihre  Geschichte  und  Lehre,  1896,  132. 


HISTORICAL  REVIEW. 

T 


Fig.  i 


rate  knowledge  of  this  phenomenon  is  to  be  ascribed  the  final 
discovery  of  the  alkali  metals.  Others  constructed  apparatus 
to  keep  the  products  of  decomposition  separate  and  to  learn 
the  composition  of  water  from  the  relations  of  the  volume  of 
the  gases.  Others  finally  busied  themselves  with  the  quali- 
ties of  the  gases  evolved  during  electrolysis.  Since  in  the 
electrolysis  of  dilute  sulphuric  acid  ozonized  oxygen 
is  evolved,  many  investigators  ascribed  to  the  evolved  hydro- 
gen especially  active  qualities.  The  works  of  Osann1,  Jamin2, 
Brunner,3  and  Crova,4  in  this  direction  were  disputed  by  de  la 
Rive5  and  A.  Brewster.6 

1  Pogg.  Ann.,  95,  311  ;  96,  510  (1855)  ;   97,  327  (1856).     J.  prakt. 
Chem.,  92,  20,  1864. 

2  Compt.  rend.,  1854,  38,  443- 

3  Mitt,  naturf.  Gesellsch.  Bern.,  1864,  555,  17. 

4  Mondes,  1864,  5,  210. 

5  Arch.  ph.  nat,  1854,  25,  275. 

6  Bull.  Soc.  Chim.,  1866,  8,  23. 


4  ELECTROLYSIS   OF   WATER. 

OLDER    LITERATURE. 

In  the  following  table  is  given  a  compilation  of  the  most 
important  older  literature  concerning  the  electrolysis  of  water, 
taken  from  Webb's  index  and  partially  enlarged. 

TABLE   I. 


Year. 

Author. 

Journal. 

Vol. 

Page. 

1780 

Troostwijk 

Journal  de  physique,  Rozier,  Paris  

2 

1  7.0 

1797 

Pearson 

Philosophical  Transactions  of  the  Royal 
Society  ,  London  

QO 

1OIJ 

1  88 

1800 

Nicholson 

Journal  of  Natural  Philosophy,  Chemis- 
try and  the  Arts,  London  

18*. 

1801 

Gautherot 

Annales  de  chimie  et  physique,  Paris  

TO 

207. 

Gilbert 

ditto                             

41 

IO7 

Pfaff 

Gilbert's  Annalen          

7 

76* 

Cruikshank 

ditto 

] 

ouo 

QI 

Klingert 

ditto             

V1 
1AQ 

Simon 

ditto             

8 

O4V 
22     17 

Davy 

ditto               

7 

1  1  A 

1803 

Simon 

Annales  de  chimie  et  physique   Paris 

AC 

4j 

l82 

1804 

Wilkinson 

Journal  of  Natural  Philosophy,  Chemistry 
and  the  Arts,  London  

2/17 

1805 

Sylvester 

ditto                   

IO 

106 

1806 

Grotthus 

Annales  de  chimie  et  physique,  Paris  

eg 

IO 

1807 

Alemani 

ditto                                 

6s 

-121 

1808 

Davy 

Gilbert's  Annalen 

28 

i   161 

1811 

Anderson 

Journal  of  Natural  Philosophy,  Chemistry 
and  the  Arts  London 

•in 

18* 

1812 

Murray 

ditto 

7  T 

L06 

87 

1830 

Bonijol 

Bibliotheque    universelle   des    sciences, 
Genf  

(1810) 

°/ 

Oct 

1832 

Bonijol 

Journal  of  the  Royal  Institution  of  Great 
Britain  

I 

2Q7 

1837 

Pouillet 

Comptes  rendus  des  stances  de  1'Acad- 
emie  des  Sciences,  Paris  

A 

78s 

1  81.9 

Becquerel 

ditto           

8 

4Q7 

Grove 

ditto           

8 

802 

Jacobi 

London,   Edinburgh   and  Dublin  Philo- 
sophical  Maga/ine 

1C 

161 

1841 

Becquerel 

Archives  de  1'electricite'    Genf 

I 

281 

1842 

De  la  Rive 

ditto 

2 

468 

Pearson 

Annals  of  Electricity,  London 

406 

Weber 

Archives  de  1'e'lectricit^    Genf  .    . 

2 

66  1 

Wollaston 

Annals  of  Electricity,  London  

Q 

5i8 

1845 

Millon 

Archives  de  I'e'lectricite',  Genf  

t: 

^03 

1851 

Vigau 

Comptes  rendus  des  stances  de  1'Acade"  - 
mie  des  Sciences,  Paris  

7,4 

774 

1852 

Jamin 

ditto                 

P 

7QO 

Leblanc 

ditto 

38 

44.4 

1853 

Kard 

London,   Edinburgh  and  Dublin  Philo- 
sophical Magazine... 

6 

241 

HISTORICAL  REVIEW. 


Year. 

Author. 

Journal. 

Vol. 

Page. 

Shepard 

British   Patent  Reports 

(185^ 

1854 

Callau 

London,  Edinburgh  and  Dublin    Philo 
sophical   Magazine 

7 

77 

Council 

ditto 

7 

426 

De  la  Rive 

Archives  des  sciences  physiques  et  nat 
urelles     Genf                     .             .  . 

25 

275 

Jamin 

Comptes  rendus  des  Stances  de  1'Acade"- 
mie  des  Sciences   Paris  

^8 

447 

Dumas 

ditto                  

^8 

444 

Foucault 

Archives  des  sciences  physiques  et  nat- 
urelles  Genf 

2C 

1  80 

Leblanc 

Comptes  rendus  des  stances  de  1'Acade"- 
mie  des  Sciences,  Paris  

38 

444 

Soret 

Archives   des  sciences  physiques  et  nat- 
urelles     Genf 

25 

175 

1855 

Buff 
Buff 

ditto 
Annalen  der  Chemie  u.  Pharmacie,  Heid- 
elberg 

31 

Q-l 

I98 
256 

Osann 

Annalen  der  Physik  u.  Chemie,  Poggen- 
dorf  Berlin    . 

95 
06 

3'i 
Sio 

1856 

Andrews 

Annales  de  chimie  et  physique   Paris 

CQ 

124 

De  la  Rive 

Comptes  rendus  des  stances  de  1'Acade*- 
mie  des  Sciences   Paris        

42 

7IO 

Despretz 

ditto                 

42 

7O7 

Osann 

Annalen  der  Physik  u.  Chemie,  Poggen- 
dorf  Berlin                                              / 

Q7 

727 

Sorel 
Soret 

Annales  de  Chimie  et  physique,  Paris  
Archives  des  sciences  physiques  et  nat- 
urelles,  Genf.  

45 
7i 

II 
2O4 

— 

[ournal  fur  praktische  Chemie,  Erdmanu, 
Leipzig  

67 

IT\ 

1857 

Breda 

Annalen   der  Physik  und  Chemie,  Pog- 
gendorf,  Berlin  

on 

6^4 

Geuther 

American    Journal  of  Science  and  Arts, 
New   Haven  

28 

281 

1858 

Fonvielle 

Comptes  rendus  des  seances  de  1'Acade"- 
mie  des  Sciences,  Paris  

47 

140 

1859 

Friedel 

Annalen    der     Chemie    und  Pharmacie, 
Heidelberg 

112 

^76 

1861 
1864  | 

Andrews 
Osann 

Journal  of  the  Chemical  Society,  London 
Journal  fur  praktische  Chemie,  Erdmann, 
Leipzig 

13 
Q2 

344 
20 

Brunner 

Mitteilungen  der  naturforschenden  Ges- 
ellschaft    Bern  

sss 

17 

Crova 

Mondes  

c 

2IO 

1866 
1867 
1868 

Brewster 
Hofmann 
Bourgoin 
Rundspaden 

Bulletin  delaSocie"te  Chimique,  Paris  
ditto                                
ditto                               
Annalen   der    Chemie    und    Pharmacie, 
Heidelberg... 

8 

TO 
10 

151 

23 
228 
206 

106 

ELECTROLYSIS   OF   WATER. 


Year. 

Author. 

Journal. 

Vol. 

Page. 

1869 

Gerland 

Annalen  der  Physik  und  Chemie,  Pog- 
gendorf,  Berlin  

177 

SS2 

Graham 

Comptes  rendus  des  stances  de  1'  Acade- 
mic des  Sciences,  Paris  

68 

IOI 

— 

Annalen  der  Physik  und  Chemie,  Pog- 
gendorf  Berlin 

1^6 

-i  17 

1870 

Hittorf 

ditto 

106 

«$i/ 

1069 

^4.8 

Rundspadeti 

Quarterly  Journal  of  Science,  Crookes, 
London  

7 

I  & 

1872 

Blanc 

Comptes  rendus  des  stances  de  1'Acade"- 
mie  des  Sciences  Paris 

7S 

ti-i'7 

187-; 

Becquerel 

ditto                   

77 

Le  Blanc 

Transactions  of  the  Chemical  Society, 
L/ondon  

26 

242 

1876 
1877 
1878 

Gladstone 
Berthelot 
Exner 

Journal  of  the  Chemical  Society,  London 
Annales  de  Chimie  et  physique,  Paris  
jSitzungsberichte    der    naturwissenchaft- 
lichen  Klasse  der  kaiserlichen  Akade- 
mie  der  Wissenschaften  zu  Wien  

(l876) 
H 

77 

152 

361 

655 

1879 

Schoene 

Journal  of  the  Chemical  Society,  London 

36 

878 

In  the  eightieth  year  of  the  previous  century  the  technical 
application  of  the  electrolysis  of  water  was  first  taken  up  and 
we  now  come  to  the  consideration  of  the  real  contents  of  the 
present  publication. 


II.  THE  CONSTANTS  OF  THE  ELECTROLYTIC  DE- 
COMPOSITION OF  WATER. 

CHEMICAL  AND  ELECTROCHEMICAL  CONSTANTS. 

For  the  purpose  of  the  easier  comparison  of  the  output  of 
the  processes  to  be  described  later,  we  will  here  collect  to- 
gether the  chemical  and  electrochemical  constants  of  the  prod- 
ucts of  the  electrolysis  of  water,  viz.,  of  oxygen,  hydrogen 
and  detonating  gas. 

A.  OXYGEN. 

Atomic  weight  =  16. 

Molecular  weight  —  32. 

Specific  gravity  =  1.10563  (air  =  i). 

i  liter  at  o°  C.  and  760  mm.  pressure  =  1.43028  gram. 

i  gram  =  699  cubic  centimeters. 

i  coulomb  sets  free  0.0829  mg-  —  °-°58  cc. 

i  ampere-hour  sets  free  0.298  gram  =  208.8  cc. 


ELECTROLYTIC  DECOMPOSITION   OF   WATER.  7 

B.  HYDROGEN. 

Atomic  weight,  i. 

Molecular  weight,  2. 

Specific  gravity,  0.06926  (air  =  i). 

i  liter  at  o°  C.  and  760  mm.  pressure  =  0.089578  gram. 

i  gram  =  11.1636  liters. 

i  coulomb  sets  free  0.0104  mg.  =  0.116  cc. 

i  ampere-hour  sets  free  0.037  gr^m  =  417.6  cc. 

C.  DETONATING  GAS. 

Specific  gravity,  0.41468. 

i  liter  at  o°  C.  and  760  mm.  pressure  =  0.53614  gram. 

i  gram  =  1865  cc. 

i  coulomb  sets  free  0.0933  mg.  =0.174  cc. 

i  ampere-hour  sets  free  0.335  gram  =  626.4  cc- 

DECOMPOSITION  VOLTAGE. 

An  approximate  value  for  the  voltage  absorbed  in  the  de- 
composition of  water,  sufficiently  close  for  technical  purposes 
can  be  obtained  by  Thomson's  rule  which  starts  from  the  as- 
sumption that  the  energy  required  for  decomposition,  that  is> 
in  our  case,  the  electrical  energy  required  must  equal  the  heat 
of  formation. 

Since  the  heat  of  formation  of  water  is  68,400  calories  and 
i  volt-coulomb  =  4.18  X  io7  ergs  =  0.2394  cals,  there  is, 
therefore,  required  for  the  electrolysis  of  a  gram-molecule  of 
water 

68,400 

—  285,714  volt-coulombs. 

O  s    r 

Since  in  the  decomposition  of  the  gram-molecule  of  water 
two  gram-equivalents  of  hydrogen  are  set  free  at  the  cathode, 
which  require,  according  to  Faraday's  law,  2  X  96540  cou- 
lombs, the  decomposition  voltage  necessarily  must  be 

285,714  volt-coulombs 

—T-         — i T—  =  1.48  or  roundly  1.5  volts. 

2  X  96,540  coulombs 

The  first  theoretical  investigations  upon,  the  electromotive 
force  necessary  to  decompose  water  were  made  by  Helmholtz,1 
who  by  different  methods  obtained  for  it  1.6447  an^  I-7^3 
volts.  LeBlanc  determined  experimentally  the  decomposition 
point  of  water  at  1.67  volts,  at  which  electromotive  force  the 

1  Ges.  Abh.,  Ill,  92  and  267. 


8  ELECTROLYSIS   OF   WATER. 

permanent  passage  of  the  current  commences.  Glaser  re- 
peated the  investigations  of  LeBlanc  in  particular  to  clear  up 
the  contradiction  that  the  H-O  cell  only  gives  1.08  volts. 
Glaser  found  at  this  latter  voltage  a  kink  in  the  decomposition 
curve,  but  ascribed  the  same  to  the  separation  of  doubly 
charged  oxygen  ions  and  explained  hereby  the  contradiction 
with  the  gas  cell.  For  further  data,  reference  is  made  to  the  orig- 
inal work.1  As  the  main  results  of  a  part  of  this  work,  Glaser 
promulgated  the  law  that  the  decomposition  of  water,  although 
it  can  take  place  primarily,  in  reality  takes  place  mostly  second- 
arily, especially  with  moderately  strong  currents. 

CONDUCTIVITY. 

The  conductivity  of  water  is,  according  to  the  work  of 
Kohlrausch,2  very  small  and  is  for  pure  distilled  water  in  a 
column  i  m.  long  and  i  sq.  mm.  cross-section,  at  18°  C. 
0.04  X  io~10  (Hg  =  i). 

For  all  practical  purposes  of  electrolytic  decomposition  of 
water  the  latter  must  first  be  made  conducting.  For  this 
purpose  acids  as  well  as  bases  are  used.  A  table  in  the  ap- 
pendix gives  data  on  resistances  and  conductivity  of  electro- 
lytes used  in  the  technical  decomposition  of  water,  that  is,  of 
sulphuric  acid,  caustic  alkalies  and  the  alkaline  carbonates. 
M.  U.  Schoop3  gives  graphical  representations  of  the  con- 
nection between  resistances  of  electrolytes  and  their  concen- 
tration. 


III.  REVIEW  OF  THE  PROCESSES. 
Although  it  would  be  attractive  and,  in  most  respects, 
justifiable  to  describe  the  various  apparatus  and  processes 
used  in  the  electrolytic  decomposition  of  water  in  a  chrono- 
logical order,  yet  the  difficulty  would  arise  in  doing  so,  that 
apparatus  of  quite  various  principles  would  come  close  to- 

1  Zeitschr.     fur    Blektrochem.,    1897-1898,     374.     See   also    Caspar!  : 
tiber  Wasserstoffentwicklung,  Zeitschr.  fur  Elektrochem.,  1899-1900,  37. 

2  Kohlrausch  :  Ztschr.  phys.  Chem.,  1894,  14,  317. 

3  Die  industrielle  Elektrolyse  des  Wassers,  1901,  113. 


REVIEW   OF   THE   PROCESSES.  9 

gether.     By  so  doing,   clearness  of  description  would  suffer. 

We  will,  therefore,  in  the  following  pages,  describe  the 
processes  by  groups  and  give  a  chronological  compilation  at 
the  close  of  this  section  in  a  tabular  form. 

The  division  into  groups  may  most  advantageously  be  made 
in  the  following  way: 

A.  Processes  and  Apparatus  for  the  Separate 

Production  of  Oxygen  and  Hydrogen. 

(a)  With  Porous  Diaphragms  of  Non-conducting  Mate- 

rial. 

(b)  With  Complete  Non-conducting  Partitions. 

(a)  For  Instruction  and  Laboratory  Work. 

(b)  For  Technical  Purposes. 

(c)  With  Complete  or  Perforated  Conducting  Partitions. 

B.  Processes  and  Apparatus  for  the   Electroly- 
sis of  Water  without  Separation  of  the  Gas 

(Production  of  Detonating  Gas). 

(a)  For  Instruction  and  Laboratory  Work. 

(b)  For  Technical  Purposes. 

C.  Processes  for  the  Simple  Evolution  of  Oxygen. 

(a)  Through  Depolarization  at  the  Cathode. 

(b)  By  the  Precipitation  of  Metal  at  the  Cathode. 


A.     Processes  and  Apparatus  for  the  Separate 
Production  of  Oxygen  and  Hydrogen. 

<a)  With  Porous  Diaphragms  of  Non-conducting  M  aterial. 

About  the  middle  of  1880  the  industrial  application  of  the 
electrolytic  decomposition  of  water  began  to  be  taken  up  and 
was  commenced  with  the  use  of  porous  diaphragms. 


10  ELECTROLYSIS   OF  WATER. 

Process  of  D'Arsonval,  1885. 

In  the  years  1885-1887  d' Arson  val1  used,  in  his  medical  lec- 
tures at  the  College  of  France,  electrolytic  apparatus  for  the 
manufacture  of  pure  oxygen  and  applied  the  same  in  his  re- 
searches upon  respiration  in  closed  spaces. 

FORM    OF   APPARATUS. 

The  apparatus  was  for  this  purpose  constructed  of  four 
similar  decomposition  cells  made  by  Branville  &  Co.,  after 
the  designs  of  d' Arsonval.  As  an  anode,  was  used  a  perforated 
iron  cylinder  placed  inside  of  a  linen  or  woolen  bag  which 
served  as  a  diaphragm.  A  30  per  cent  solution  of  caustic 
potash  was  used  as  electrolyte.  D'Arsonval  observed  no  cor- 
rosion of  the  iron  anode.  The  cathode  consisted  of  a  cylin- 
drical vessel  of  sheet-iron  2  dcm  in  diameter  and  6  dcm  high. 
Each  decomposition  cell  was  intended  for  a  current  of  about 
60  amperes,  from  which  the  current  density  of  not  quite  2 
amperes  per  sq.  dm.  of  cathode  surface  may  be  calculated. 
D'Arsonval  has  given  no  data  about  the  applied  electromotive 
force. 

The  oxygen  was  collected  and  the  hydrogen  allowed  to  escape 
unused.  The  apparatus  was  in  constant  use  for  laboratory 
purposes  only,  and  furnished  per  day  100-150  litres  of  oxygen, 
as  required.  The  apparatus  is  said  to  have  worked  satisfac- 
torily, except  for  the  frequent  renewal  of  the  diaphragm. 

D'Arsonval  was  about  to  describe  his  arrangement  of  appa- 
ratus at  a  meeting  of  the  Physical  Society  of  Paris  in  the 
beginning  of  1888,  when  he  heard  of  the  somewhat  better 
construction  of  LatchinofPs  apparatus  introduced  about  this 
time.  Soon  thereafter  followed  the  work  of  Renard  on  the 
same  subject.  D'Arsonval  had,  therefore,  to  content  himself 
with  confirming  the  already  published  results,  and  by  doing  so 
illustrated  the  often  observed  fact  that  many  experimenters, 
quite  independently  of  each  other,  can  arrive  at  similar  results. 

1  Elektrotech.    Zeitschr.    Uppenborn,    1891,   197.      Grawinkl-Strecker : 
Hilfsbuchf.  Elektrotech.     Stohman-Kerl :  Tech.    Chemie,  VII,  714. 


PROCESS   OF   LATCHINOFF  II 

Process  of  Latch inoff. 

On  the  20th  of  November,  1888,  D.  Latchinoff,  of  St. 
Petersburg,  received  the  German  patent  51,998,*  for  an  "  ap- 
paratus for  the  obtaining  of  hydrogen  and  oxygen  by  elec- 
trolysis." 

PATENT  CIvAIM. 

The  patent  claim  runs  : 

uAn  arrangement  of  apparatus  for  the  obtaining  of  hydro- 
gen and  oxygen  on  a  large  scale,  by  electrolytic  decomposi- 
tion of  acid  or  slightly  alkaline  water,  consisting  in  the  com- 
bination of  a  direct  current  dynamo,  one  or  more  parallel 
connected  batteries  of  decomposition  cells  with  arrangements 
for  the  separate  collection  of  the  two  evolved  gases,  drying 
apparatus  for  each  of  the  two  gases,  as  well  as  gasometers  for 
the  storing  of  the  latter,  and  with  the  gas  exits  from  the  cells 
provided  in  such  manner  with  floating  valves,  that  the  varia- 
tions of  pressure  in  the  divisions  of  the  cell  automatically 
-equalize  themselves." 

LatchinofT  used  either  the  iron  electrodes  with  an  alkaline 
electrolyte  (10  per  cent,  solution  caustic  soda)  like  d'Arsonval 
or  two  carbon  cathodes  with  one  lead  anode  in  10-15  percent, 
sulphuric  acid. 

FIRST   METHOD  OF  OPERATION. 

The  arrangement  of  the  apparatus  is  shown  in  Figs.  2 
and  3a.  The  electrolyte  is  in  a  vessel  made  of  stoneware, 
clay  or  glass,  in  which  the  level  of  the  liquid  can  be  observed 
in  an  external  lip,  c.  A  bell,  </,  serves  for  collecting  the  gas, 
and  is  provided  with  a  flange,  f,  which  rests  on  the  edge  of  the 
outside  vessel.  The  bell  dips  6  cm.  into  the  electrolyte  and 
is  divided  into  three  sections  corresponding  to  the  three  elec- 
trodes #,  £,  a.  The  tubes,  g  and  ^,  lead  to  the  gasometers. 

1  Ausziige  aus  der  Patentschrift,   Patentblatt,  II,  506,  I.  Chem.   Central- 
,blatt,  1890,  II,  640.  Chem.  Ztg.,  1890,  55,  906. 

2  I^a  lumiere  £lectrique,  4O,  234. 


12 


ELECTROLYSIS   OF   WATER. 
9 


Fig.  2. 


Fig.  3- 


In  order  to  prevent  the  mixing  of  hydrogen  and  oxygen  in 
the  electrolyte,  two  asbestos  curtains  stretched  on  a  paraffined 
ebonite  frame  were  hung  between  the  electrodes,  reaching 
down  to  the  bottom  of  the  stoneware  vessel  and  up  to  the  par- 
titions of  the  gas  bell. 

Latchinoff  carried  on  his  investigations  with  electrodes  3 
dm.  wide  and  5  dm.  high,  and  used  a  current  density  of  14 
amperes  per  sq.  dm. 

The  single  cells  were  placed  in  series  and  insulated  from 
ground  connections  by  three  porcelain  insulators  which  stood 
upon  an  asphalted  plate. 

LATER  METHODS  OF  OPERATION. 

The  first  practical  form  of  the  Latchinoff  apparatus  was 
found  to  be  too  easily  broken  when  constructed  on  a  larger 
scale.  Latchinoff  changed  to  another  type  of  apparatus  in 


PROCESS   OF   LATCHINOFF. 


which  the  outer  vessel  was  made  of  metal  and  also  served  as 
the  cathode.1 

In  Figs.   4  and  5,  a  a  indicates  a  square  vessel  of  cast-  or 
wrought-iron.    This  is  enlarged  above  and  carries  a  bell,  d,  rest- 

I 


|i 

j| 

d 

i 

2 

^ 
3L 

i 

B 

^P 

E2 

I 

>^§ 

^si§ 

• 

2 

% 

Ih 

Fig.  4. 


Fig.  5- 


ing  uponyC     The  vessel  a  is  provided  with  an  overflow,  £,  and 
is  insulated  by  insulators  and  wooden  stringers. 

The  cathode  is  formed  by  the  vessel  a  itself  while  the  piece 
of  sheet-iron  b  serves  as  anode.  The  latter  is  surrounded  by 
a  box  made  of  ebonite  strips  covered  with  parchment  paper. 
The  anode  receives  the  current  by  an  insulated  wire  introduced 
through  the  overflow  underneath  the  lower  edge  of  the  bell. 
The  bell  d,  likewise  of  iron,  is  divided  into  two  spaces,  which 
are  in  connection  with  the  gas  pipes  by  the  T-joints,  g  and  k. 

1  Zeitschr.  f.  Elektrot.,  1894,  338,  364  and  382.    Electrochem.  Zeitschr., 
1894-95,  1 06. 


14  ELECTROLYSIS   OF   WATER. 

Since  the  bell  d  is  in  electrical  connection  with  the  cathode 
vessel,  the  lower  part  of  the  inner  chamber  of  d  is  lined  with 
hard  rubber  above  the  level  of  the  liquid,  in  order  not  to  con- 
taminate the  oxygen  passing  into  it,  by  hydrogen  which  might 
be  thereupon  developed.  In  the  apparatus  the  electrolyte  was 
also  a  10-15  per  cent,  solution  of  caustic  soda  as  free  as  possible 
from  carbonates. 

The  apparatus  containing  not  quite  60  litres  required  300 
amperes.  The  anode  measured  9x5  dm.  and  had  therefore 
on  both  sides  90  sq.  dm.  surface.  The  outer  vessel  measured 


Fig.  6. 

50x100x11  cm.  The  current  density  at  the  anode  was  there- 
fore 3.5  amperes  per  sq.  dm.  The  single  cells  were  connected 
up  as  shown  in  Fig.  6. 

The  gases  were  collected  by  a  series  of  pipes  with  connec- 
tions to  each  apparatus,  and  dried  before  going  to  the  gasom- 
eter. 

DRYING  OF  THE  GASES. 

For  a  drying  chamber  a  long  box  with  rounded  cover  was 
used,  with  a  partition  reaching  not  quite  to  the  bottom,  and 
on  both  sides  of  the  partition  lay  a  quantity  of  pumice  stone 


xcr* 

S         or 
{    UNIV 


UNIVERSIT 


PROCESS  OF  LATCHINOFF.  15 

soaked  with  sulphuric  acid.  The  gases  entering  into  one  side 
of  the  partition  were  forced  to  pass  through  the  pumice,  under 
the  partition,  and  up  on  the  other  side.  The  gases  are  there- 
fore not  only  dried  but  also  freed  from  any  particles  of  alka- 
line electrolyte  carried  out  with  them. 

MODERATION  OF  COMPLICATIONS. 

To  avoid  irregularities  in  the  electrical  decomposition,  mer- 
cury manometers  are  provided  which  are  connected  with  one 
pole  of  an  alarm  bell.  The  second  pole  of  the  alarm  bell  was 
connected  to  a  platinum  wire  sealed  into  the  upper  part  of  the 
manometer  tube.  When  the  pressure  rises  in  the  apparatus 
the  mercury  is  forced  up  the  tube  of  the  manometer  and  when 
it  reaches  the  platinum  wire  mentioned,  completes  the  circuit 
and  rings  the  bell. 

BIPOLAR  CONNECTIONS. 

Latchinoff  was  the  first  to  use  bipolar  electrodes  in  the 
electrolytic  decomposition  of  water.  For  smaller  plants  as  in 
laboratories,  pharmacies,  etc.,  a  long  box  about  2  metres  long 
made  of  paraffined  wood  is  divided  by  air-tight  electrode  plates 
into  a  series  of  chambers.  Between  the  electrodes  were  placed 
diaphragms  of  parchment.  All  the  intermediate  partitions 
acted  as  double  plates  since  only  the  two  external  ones  were 
connected  with  the  source  of  the  electric  current.  An  appa- 
ratus with  about  40  electrodes  could  therefore  be  connected  di- 
rectly to  a  normal  lighting  circuit.  Latchinoff  used  a  current 
density  of  about  10  amperes  per  sq.  dm.  of  electrode  surface 
for  such  an  apparatus. 

Dr.  O.  Schmidt,  as  we  shall  see  later,  has  used  recently  this 
principle  of  bipolar  arrangement  of  electrodes  in  a  practical 
apparatus,  but  Latchinoff  was  the  first  to  propose  it  for  the  de- 
composition of  water. 

ELECTROLYSIS  UNDER  PRESSURE. 

Likewise  Latchinoff  was  the  first  to  propose  and  carry  out 
in  a  decomposition  apparatus  the  compression  of  the  gases. 


16 


ELECTROLYSIS  OF  WATER. 


a 


Proceeding  from  the  assumption  that  even  considerable  pres- 
sure would  be  without  influence  upon  the  output,  he  arranged 
the  apparatus  so  that  it  was  connected  directly  with  a  steel 
tube  intended  to  stand  a  gas  pressure  of  100-120  atmospheres. 
The  apparatus  shown  in  Fig.  7  consists  of  a  cylindrical  steel 
vessel  which  is  closed  by  a  cover  tightly  screwed  on.  The  tubu- 
lar iron  electrode  b  in  the  middle  of  the  tube  is  raised  upon 
an  insulating  stand,  g.  It  is  connected  with  the  binding  post 

/by  an  insulated  wire,  k.  The 
second  binding  post  /'  is  di- 
rectly screwed  into  the  steel  cyl- 
inder, which  forms  the  second 
pole. 

The  cover  carries  two  pipe 
connections,  one  in  the  middle 
and  the  second  on  one  side. 
At  the  lower  edge  of  the  tubes 

V         |^=lf|E^£|  =  is  a  conical    valve,    supported 

^S     |=  =?|     /^    upon  a  cylindrical  float,  which 

/  inkfll^M^E^L^  jffll/      latter  works  on  a  guiding  tube 

not  shown  in  the  drawing.  An 
insulated  cylinder,  whose  lower 
part  dips  into  the  electrolyte, 
serves  to  prevent  the  mixing  of 
the  gases.  The  insulating  stand 
g,  with  its  flaring  sides  opening 
upwards,  serves  to  direct  any 
gas  evolving  from  the  bottom 
of  the  steel  cylinder  towards 
the  sides  of  this  cylinder,  so  that  it  rises  into  the  outer  space 
at  the  top. 

The  apparatus  is  filled  three-fourths  full  of  caustic  soda 
solution.  The  tube  connections  e  and  a  are  joined  with  the 
steel  cylinder  in  which  the  gases  are  to  be  compressed.  The 
oxygen  reservoir  must  only  be  one-half  as  large  as  the  hydro- 


PROCESS  OF  LATCHINOFF.  1 7 

gen  reservoir  in  order  that  the  gas  pressure  remains  the  same. 
It  is,  however,  impossible  to  avoid  small  variations  in  pressure 
which  would  lower  the  level  of  the  liquid  in  one  of  the  elec- 
trode spaces,  and  thereby  give  opportunity  for  the  formation 
of  detonating  gas. 

This  danger  is  avoided  by  the  use  of  the  floating  valves  a1  e' . 
As  soon  as  the  level  of  the  liquid  rises  higher  in  one  of  the 
compartments  the  valve,  as  for  instance  a1 ',  rises  with  the  rising 
electrolyte  and  closes  the  gas  exit,  whereupon  the  gas,  being 
still  evolved,  reduces  the  level.  As  soon  as  the  valve  is 
no  longer  held  in  place  by  the  float  it  falls  back  and  allows 
the  gas  in  question  to  pass  out.  This  provides  an  automatic 
regulator  to  the  pressure. 

Unfortunately,  there  is  in  the  literature  of  the  subject  no 
information  as  to  whether  this  apparatus  was  tried  on  a  large 
scale,  and  whether  or  in  what  manner  the  increasing  absorp- 
tion of  the  gases  in  the  electrolyte  by  increased  pressure  made 
itself  noticeable. 

PLANT. 

LatchinofT  gives  the  following  figures  for  an  industrial 
plant1 : 

A  50  H.  P.  source  of  energy  drives  a  direct  current  dynamo 
furnishing  300  amperes  and  no  volts.  The  electrolytic  plant 
consists  of  44  baths,  each  one  1.4  metres  high,  and  requires 
5x1^  metres  of  floor  space.  The  number  of  cells  therein 
mentioned  in  the  journals,  namely,  40  in  series,  must  be  a 
mistake,  since  in  this  case  the  production  named  would  be 
theoretically  scarcely  possible.  Latchinoff  used  44  cells 
which  number  he  also  mentions  in  another  place  as  using 
with  a  100  H.  P.  plant  and  no  volts  working  tension. 

A  50  H.  P.  plant  produces,  per  hour,  5.5  cubic  metres  of 
hydrogen  and  2.75  cubic  metres  of  oxygen  or  together  8.25 
cubic  metres  of  gas,  or  100  cubic  metres  of  oxygen  and  200 
cubic  metres  of  hydrogen  in  thirty-six  hours,  decomposing  150 
litres  of  water. 

1  Elektrochemische  Zeitschr.,  1894-95,  108. 


1 8  ELECTROLYSIS  OF  WATER. 

OUTPUT. 

The  theoretically  possible  output  would  be  626.4  X  300  X 
44X36  =  297.6  cubic  metres  of  gas.  Latchinoff  has,  there- 
fore, assumed  a  theoretical  current  output  and  has  reckoned 
out  with  reference  to  the  chosen  voltage  used  an  energy  out- 
put of  57.6  per  cent. 

COST  OF  OPERATION. 

Ivatchinoff  has  also  given  estimations  of  the  working  cost 
of  his  process.  In  order  to  be  able  to  compare  the  calculated 
cost  of  production,  we  will  assume  always  two  extreme  cases, 
namely,  when  power  costs  on  the  one  hand  %  cent  per  kilo- 
watt-hour for  water  power,  and  on  the  other  hand  i  J^  cents 
for  steam  power  in  small  plants.  The  data  of  Latchinoff 
would  then  reckon  up  for  the  manufacture  of  100  cubic 
metres  of  oxygen  and  200  cubic  metres  of  hydrogen  in  thirty- 
six  hours  as  follows : 

1 188  kilowatt  hours $2.97  $14.85 

Caustic  soda 0.08  0.08 

Drying  of  gases 0.24  0.24 

Attendance 4.05  4.05 

Total 7.34  19.22 

Therefore,  according  as  to  whether  only  the  oxygen,  or 
only  the  hydrogen,  or  both  gases  are  assumed  as  salable,  we 
make  these  calculations : 

a.  With  water  power,  i  cubic  metre  of  oxygen  costs  7.34  cents. 

i  cubic  metre  of  hydrogen  costs        3.67  cents, 
i  cubic  metre  of  detonating  gas  costs  2.45  cents. 

b.  With  steam-power,  i  cubic  metre  of  oxygen  costs  19.22  cents. 

i  cubic  metre  of  hydrogen  costs        9.61  cents, 
i  cubic  metre  of  detonating  gas  costs  6. 40  cents. 

Sinking  fund  and  interest  on  the  capital  invested  are  not 
included  in  these  figures. 

PRACTICE. 

It  is  not  known  whether  plants  after  Latchinoff's  methods 
have  been  industrially  operated.  The  apparatus  is  said  to 
have  been  publicly  exhibited  in  the  IV  Blectrotechnical 


PROCESS   OF    DUCRETET. 


Exposition,  opened  the  24th  of  January,  1892,'  at  St.  Pete  s- 
burg.  The  baths  were,  however,  injured  by  an  accident  at 
the  exposition,  so  that  instead  of  being  in  continual  operation, 
as  was  intended,  they  were  only  operated  a  short  time. 


Several  French  investigators  were  working  on  the  problem 
of  the  technical  electrolysis  of  water  simultaneously  with 
Latchinoff,  and,  according  to  all  appearances,  independent  of 

him. 

Process  of  Ducretet,  1888. 

Ducretet,  for  instance,  constructed  many  forms  of  apparatus 
for  the  decomposition  of  water,  using  alkaline  electrolytes. 

FORM  OF  APPARATUS. 

One  of  these  forms  of  apparatus 
is  shown  in  Fig.  8.  The  iron  cyl- 
inder E'  serves  at  the  same  time  as 
an  electrode  and  container  for  the 
electrolyte.  The  bottom  i  is  covered 
with  an  insulating  layer  and  bears 
the  supply  tube  T'.  The  cover  Co 
is  insulated  and  is  screwed  on  the 
tube.  One  of  the  connections,  £,  is 
united  with  a  centrally  placed  cylin- 
der made  of  iron  wire  netting,  which 
forms  the  second  electrode.  The 
cylindrical  asbestos  diaphragm  S  S 
divides  the  tube  into  an  anode  and 
a  cathode  space,  and  the  gases  es- 
cape at  T'  and  G'.2 

Process  of  Renard,  1888  to  189O. 
The  construction  of  Renard  rests 
on  a  similar  principle.  He  began 
his  work  in  electrolytic  decom- 
position in  1888  and  communicated 
his  results  obtained  in  a  stance  of  the 

1  Chem.  Ztg.,  1892,  28,  461.     Elektrochemische Zeitschr,  1894-95,  106. 

2  La  lumi£re  £lectrique,  4O,  234. 


20  ELECTROLYSIS   OF   WATER. 

French  Physical  Society,  December  5,  1890.  Renard  took  up 
the  question  primarily  as  commander  of  the  balloon  corps  at 
Chalais,  and,  in  consequence  of  this,  had  in  view  a  simple  and 
cheap  method  of  obtaining  hydrogen  for  the  filling  of  balloons* 

OUTPUT. 

Renard  gives  the  following  output  as  obtained  in  a  practi- 
cal application  of  his  apparatus.1 

Volume  of  hydrogen  at  io°C  and  760  mm.  0.433  litre,  per  ampere-hour. 

"      "     0.144  litre,  per  watt-hour. 

Ampere-hours  consumed  per  cubic  metre  of  hydrogen,  2310. 
Watt-hours  "  "        "          "  "  6930. 

H.  P.  hours  "  "        "          "  "  9.4 

Renard  assumed,  therefore,  nearly  a  theoretical  current  out- 
put, and  at  a  working  voltage  of  3  volts,  a  useful  energy  effect 
of  about  50  per  cent. 

He  worked  on  the  theory  that  the  platinum  used  in  the 
laboratory  apparatus  for  the  decomposition  of  water  may  be 
replaced  by  a  cheaper  material,  and,  besides  that,  he  tried  to 
find  a  diaphragm  which  would  separate  the  gases  without  in- 
troducing too  much  resistance. 

In  consequence  of  these  endeavors,  he  replaced  acid  electro- 
lytes by  alkaline  solutions  and  hereby  was  enabled  to  use  cast- 
iron  or  steel  as  electrode  materials.  Since  clay  diaphragms 
showed  too  high  a  resistance  for  the  purpose  in  view,  Renard 
used  asbestos  as  a  diaphragm  material,  its  resistance  being 
practically  negligible. 

As  an  electrolyte,  he  used  a  13  per  cent,  solution  of  caustic 
soda,  the  resistance  of  which  is  the  same  as  that  of  a  27  per 
cent,  solution  of  sulphuric  acid. 

FORM  OF  APPARATUS. 

The  simplest  construction  used  at  Chalais  consisted  of  a 
large  cylindrical  sheet-iron  vessel,  which  acted  simultaneously 
as  cathode  and  a  container  for  the  electrolyte.  A  perforated 
sheet-iron  cylinder  which  hung  from  the  insulated  cover  of 

1  La  lumiere  electrique,  39,  39. 


PROCESS  OF    DUCRETET.  21 

the  vessel,  served  as  anode.     An  asbestos  sack  drawn  over  this 
served  as  a  diaphragm. 

This  consists  of  exactly  the  same  principle  of  construction 
as  was  seen  in  the  apparatus  of  Ducretet. 

Renard  showed  to  the  French  Physical  Society  two  types 
of  apparatus,  one  weighing  2  kg.,  using  a  current  of  25  am- 
peres at  2.7  volts,  while  the  second  was  intended  for  a  current 
of  365  amperes  at  2.7  volts,  and  furnished  158  litres  of  hy- 
drogen per  hour.  The  price  of  an  apparatus  of  this  latter  size 
was  given  as  $20. 

PRACTICE. 

Such  an  apparatus  was  in  operation  at  Chalais  for  six 
months,  and  at  the  end  of  this  time  both  electrodes  and  dia- 
phragms were  in  the  best  of  condition. 

According  to  the  report  of  Renard  the  hydrogen  obtained 
was  pure  and  the  oxygen  free  from  ozone  in  consequence 
of  the  alkaline  solution,  so  that  the  use  of  rubber  for  connec- 
tions was  permissible.  The  gases  were  washed  with  tartaric 
acid  in  order  to  remove  the  spray  of  the  alkaline  solutions. 

COST  OF  PLANT  AND  OPERATION. 

The  cost  of  a  plant  which  used  36  of  the  larger-sized  elec- 
trolyzers,  and  furnished  5.7  cubic  metres  of  hydrogen  and 
2.85  cubic  metres  of  oxygen  per  hour  (=136  cubic  metres  of 
hydrogen  and  68  cubic  metres  of  oxygen  per  24  hours),  was 
estimated  by  Renard  to  be  $8100  and  the  cost  of  operation, 
including  the  compression  of  the  gas  to  120  atmospheres,  10 
to  12  cents  per  cubic  metre  of  hydrogen.  It  was  assumed  in 
these  figures  that  2x/5  pounds  of  coal  would  be  used  per  H.  P. 
hour  in  generating  current. 

LABORATORY  APPARATUS. 

Besides  the  apparatus  for  the  technical  manufacture  of  hy- 
drogen for  the  filling  of  balloons,  Renard  constructed  also 
larger  laboratory  apparatus  which  were  then  furnished  by  Du- 
cretet in  Paris1. 

1  La  lumiere  £lectrique,  43,  432. 


22 


ELECTROLYSIS   OF   WATER. 


These  apparatus  were  very  similar   to  the  above-described 
Ducretet  apparatus  and  are  shown  in  Fig.  9. 


Fig.  9. 

This  laboratory  model  measured  40  cm.  high,  18  cm.  diam- 
eter, and  could  take  a  current  of  60  amperes  using  4.5  volts. 
The  production  was  26  litres  of  hydrogen  and  13  litres  of  oxy- 
gen per  hour.  With  a  normal  tension  of  three  volts  the  ap- 
paratus passed  25  amperes,  producing  n  litres  of  hydrogen 
and  5.5  litres  of  oxygen  per  hour.  The  materials  used  and 
the  electrodes  were  the  same  as  in  the  formerly  described  ap- 
paratus of  Ducretet.  Instead  of  asbestos  diaphragms  clay  cylin- 
ders were  used,  in  order  to  obtain  very  pure  gases.  In  this 
case  the  cylinders  are  perforated  at  the  bottom  and  contained 
a  bent  tube,  S,  which  connected  the  two  electrode  chambers. 

The  electrolyte  was  poured  in  at  M.     The  two  gas  bottles 


PROCESS   OF   DELMARD. 


Gh  and  Go  served  to  equalize  the  differences  of  pressure,  an 
contained  a  5  per  cent  solution  of  tartaric  acid  to  absorb  the 
alkaline  spray  carried  over.    As  the  current  density  increased, 
the  voltage  used  and  the  output  increased   in   the  following 
manner :  TABLE  II. 


Amperes. 

Volts. 

Litres  hydrogen 
per  hour. 

Litres  oxygen 
per  hour. 

Temperature. 

2 

2.06 

0.87 

0-43 

25-5° 

5 

2.24 

2.16 

1.  08 

10 

2.41 

4-33 

2.16 

20 

2.84 

8.66 

4-33 

25 

3-°4 

10.82 

5-41 

40 

3.65 

17.32 

8.66 

5° 

4.00 

21.65 

10.82 

60 

4.40 

26.00 

13.00 

Process  of  Delmard,  189O. 

The  principle  of  construction  as  used  by  Ducretet  and  Ren- 
ard  was  patented  in  Germany  by  Delmard  in  the  German  pat- 
ent 58,282  of  November  23,  1890. 

The  patent  claim  embraces  : 

1.  "An  electrolytic  apparatus  for  the  decomposition  of  wa- 
ter consisting  of  an  iron  vessel,  g^  in  which  an  iron  tube,  #, 
provided  with  perforations,  0,  and  surrounded  by  a  sack  of  as- 
bestos cloth,  is  hung  from   the  cover  /,  and  insulated  there- 
from, said  cover  being  provided  with  two  pipe  connections  for 
the  taking  off  of  the  hydrogen  and  oxygen,  and  so  arranged 
that  the  outer  vessel  forms  the  +  and  the  inner  tube  h  the 

-  electrode."     (See  Fig.  10.) 

2.  "  In  combination  with  the  apparatus  described  under  i, 
a  pressure  regulator  consisting  of  the  vessels  A  and  B   con- 
nected by  a  tube,  T,  close  to  their  bases,  into  which  vessels  the 
hydrogen  and  oxygen  coming  from  the  generator  are  led  by 
the  tubes  O  and  H,  which  dip  to  the  same  level  in   the  two 
vessels,  atmospheric  air  being  excluded."     (See  Fig.  n.) 

It  is  not  necessary  to  further  describe  these  patent  specifi- 
cations since  they  furnish  nothing  new  compared  to  Ducretet 
and  Renard.  The  apparatus  is  merely  as  compared  with  these 
latter  considerably  longer. 


ELECTROLYSIS  OF  WATER. 


Fig.  10. 


It  is  quite  probable  that  this  patent  is 
only  a  German  patenta  pplication  of  Ren- 
ard's  under  a  strange  name. 

Nothing  is  known  of  any  industrial  ap- 
plication of  this  type  of  apparatus,  espe- 
cially in  Germany. 

Process  of  Bell,  1893. 
We  first  find  something   new   in  appa- 
ratus for  the  decomposition  of  water,  using 


Frg.  ii. 


porous  diaphragms  in  the  German  patent 
78,146  of  October  30,  1893,  describing  the 
apparatus  of  Bell.1 


PATENT  CLAIM. 

Patent  claim  : 

uAn  arrangement  for  the  continuous 
charging  of  apparatus  for  the  electrolytic 
decomposition  of  fluids,  in  which  the  elec- 
trodes are  separated  from  each  other  by  a  partition,  consisting 
therein,  that  these  partitions  themselves,  or  an  extension  of 

1  Extracts  in  Zeitschr.  Elektrochein.,  1894-95,429.  Jahrbuch  f .  Elektro- 
chemie,  1895,  193.     Ahrens:  Handbuch  der  Elektrochemie,  1896. 


PROCESS  OF  BEIvL.  25 

the  same  made  of  capillary  netting  or  a  similar  material,  have 
their  upper  edge  turned  over  and  dipping  into  the  vessel  g  g 
above  the  decomposition  space  and  filled  with  an  electrolyte 
or  another  suitable  fluid  by  a  funnel,  z,  and  out  of  which  the 
electrolyte  or  other  fluid  is  sucked  up,  and  by  the  proper  reg- 
ulation of  the  level  of  the  fluid  in  the  vessel  g  g  furnishes 
to  the  electrodes,  by  the  principle  of  capillarity  and  gravity,  a 
fresh  quantity  of  fluid  as  the  latter  is  decomposed." 

FORM  OF  APPARATUS. 

The  apparatus,   as  shown  in   Fig.  12,  contains  on  a   base 


1 


plate,/,  two  concentric  hollow  cylinders,  ^and  c^  of  cast-iron, 
which  are  described   in  the  patent  specifications  as  being  of 


26  ELECTROLYSIS   OF   WATER. 

circular  section.  Both  cylinders  are  insulated  from  each  other 
by  a  non-conducting  clamp,  f,  and  covered  by  an  insulated 
cover,  d.  The  funnel  g  passes  through  the  middle  of  the  cover 
which  contains  an  inverted  conical  tube,  r.  An  asbestos  web, 
s,  in  which  is  interwoven  vertical  vegetable  fibres  of  linen  or 
wool,  hangs  between  the  electrodes.  The  lower  end  of  the 
cylindrical  diaphragm  is  fastened  to  the  hard  rubber  clamp 
surrounding  the  one  electrode  holder,  while  the  upper  end  is 
turned  over  the  tube  r.  The  funnel-shaped  vessel  Discovered 
with  an  air-tight  cover,  in  the  center  of  which  a  funnel-shaped 
tube,  t,  is  fastened  by  means  of  a  stopper,  and  reaches  down  al- 
most to  the  upper  end  of  the  electrode  C.  The  outer  contain- 
ing vessel  C  carries  the  nipple  D,  on  the  end  of  which,  as  well 
as  on  the  end  of  the  tube  ^,  the  rubber  tubes  serving  to  carry 
off  the  gases  may  be  slipped.  A  copper  band,  £,  which  sur- 
rounds the  outside  hollow  cylinder,  takes  the  current  to  the 
negative  pole,  while  the  positive  conductor  is  connected  to  the 
inner  cylindrical  electrode  by  means  of  the  plate  a,  in  contact 
with  the  base  plate/.  The  spaces  between  the  electrodes  and 
the  diaphragm  were  filled  to  n  with  pieces  of  cast-iron  or  some 
other  broken  conducting  material  which  is  not  attacked  by 
the  electrolyte.  This  makes  a  coherent  conducting  layer 
which  reaches  to  the  diaphragm. 

This  direct  contact  of  the  electrodes  with  the  diaphragm  is 
obtained  by  Bell  by  still  other  arrangements,  such  as  by  two 
narrow  spirals  of  steel  wire  upon  which  the  asbestos  mantel 
is  clamped.  In  this  case  the  inner  cylinder  can  be  completely 
omitted  while  the  outer  cylinder  serves  as  a  container.  In 
this  the  fundamental  condition  is  always  that  the  gases  evolved 
must  be  able  to  escape  easily. 

The  electrolyte  is  poured  in  through  the  siphon-shaped  fun- 
nel i  connected  with  g.  A  15  per  cent,  solution  of  caustic 
soda  is  used  for  electrolyte.  The  electrolyte  is  run  in  until 
it  flows  over  the  edge  of  r  and  runs  down  the  asbestos  mantel 
into  the  apparatus.  After  that  the  asbestos  mantel  absorbs 


PROCESS    OF   SCHMIDT.  27 

the  electrolyte  constantly  by  capillary  action.     The  height  of 
the  electrolyte  can  be  observed  in  the  tube  kT. 

Fig.  13  shows  a  cross-section  through  the  two  electrodes 
and  the  diaphragm,  while  Fig.  14  shows  another  arrangement 


Fig.  13.  Fig.  14. 

which  gives  to  the  diaphragm  and  therefore  also  to  the  elec- 
trode surfaces  a  greater  area. 

Although  the  thought  of  obtaining  the  greatest  possible 
electrode  surface  by  this  filling  with  metallic  granules  is  quite 
reasonable,  yet  we  must  not  leave  out  of  consideration  that 
the  electrodes  may  be  coated  over  by  impurities  which  sepa- 
rate out  during  electrolysis,  and  thereby  produce  difficulties 
in  the  operation. 

PRACTICE. 

It  is  not  known  that  this  apparatus  has  gone  into  prac- 
tical use.  The  whole  construction  reminds  one  more  of  a 
simple  laboratory  research,  as  seems  particularly  indicated  by 
the  three  set-screws  F  which  are  only  used  upon  instruments 
requiring  fine  adjustment.  These  are  for  the  purpose  of 
making  an  exact  horizontal  adjustment  of  the  edge  of  the 
diaphragm  above  r. 

After  the  above-described  attempts  of  Bell,  practical  electro- 
chemists,  who  worked  on  the  electrolytic  decomposition  of 
water,  turned  to  other  principles  of  construction  which  will  be 
described  in  the  latter  part  of  this  work,  while  the  use  of 
porous  diaphragms  fell  more  into  the  background. 

Process  of  Schmidt,  1899. 

It  was  not  until  the  year  1889  that  Dr.  O.  Schmidt  returned 
to  the  use  of  porous  diaphragms  and  obtained  a  patent  for  the 


28  ELECTROLYSIS   OF  WATER. 

apparatus  described  in  the  German  patent   111,131,  June  13, 
1899.' 

PATENT  CLAIM. 

Patent  claim : 

"An  apparatus  for  the  electrolysis  of  water  consisting  of 
many  series  of  plates  after  the  fashion  of  a  filter  press,  and 
characterized  by  having  the  pipes  for  conducting  off  the  gases 
communicating  with  the  water  supply  pipes,  for  the  purpose 
of  taking  back  into  the  electrode  compartments  the  water  car- 
ried out  by  the  gases." 

DESCRIPTION. 

The  fundamental  idea  of  the  Schmidt  invention  consists, 
therefore,  in  an  apparatus  with  numerous  cells  placed  like  a 
filter-press  and  characterized  by  the  fact  that  the  current  com- 
municated to  the  water  in  the  direction  of  the  gas  exits,  by 
the  evolution  of  the  gas,  causing  a  large  outflow  of  water,  is 
converted  into  a  rapidly  circulating  system.  This  is  obtained 
by  making  the  gas  exit  pipes  connect  with  a  vessel  called  the 
gas  separator  which  connects  with  the  pipes  furnishing  the 
cells  with  water.  Since  the  water  carried  out  by  the  gases  is 
thus  returned  to  the  electrolyte  in  the  cells,  very  little  loss  of 
electrolyte  ensues. 

The  apparatus  is  shown  in  one  example  in  Figs.  15-18,  in 
the  form  in  which  the  electrodes  are  connected  in  series. 

Fig.  15  shows  the  apparatus  in  side  elevation,  Fig.  16  in 
horizontal  section,  Fig.  17  a  front  view  of  one  of  the  frames 
as  seen  from  the  anode  side,  and  Fig.  18  is  a  vertical  middle 
section  through  the  gas  separator  O  for  the  oxygen.  £,  e  are  the 
double  pole  electrodes  touching  each  other  at  the  thick  edges, 
and  d  the  diaphragms  placed  in  between  the  electrodes  to 
produce  the  electrode  spaces  and  simultaneously  insulate  the 
edges  of  the  electrodes  from  each  other. 

Each  plate,  <?,  has  at  top  and  bottom,  in  its  thick  edges,  two 

1  Descriptions  in  Zeitschr.  Elektrochemie,  1900-01,  294.     Elektrochem. 
Zeitschr.,  igoo-'oi,  230. 


PROCESS    OF  SCHMIDT. 


bore-holes  h  0and  w  w1  (Fig.  17),  so  that  the  apparatus  is  pene- 
trated above  and  below  by  two  channels,  the  lower  one  serv- 
ing to  supply  the  electrode  spaces  with  water  and  the  upper 


Fig.  18. 


Fig.  16. 


Fig.  17. 


for  the  leading-off  of  the  evolved  gases,  since  w  and  h  are  each 
connected  with  the  cathode  spaces  and  w1  and  o  each  with 
the  anode  spaces. 

The  two  water  channels  w  and  w1  at  one  end  of  the  appa- 
ratus communicate  by  the  tube  w2  w2  with  a  common  water 
escape  W,  and  at  the  opposite  end  the  two  gas  channels  h  and  o 
are  each  in  connection  with  the  gas  separators  for  hydrogen  and 
oxygen  through  the  tubes  }f  and  o1  (the  latter  covered  by  the 
former  in  Fig.  15).  Regarding  the  two  gas  separators,  .//com- 
municates by  the  down-take  tube  w3  with  the  water  channels 
w  and  0,  and  moreover,  likewise  communicates  with  the  water 
channel  w1  at  this  end.  The  gas  separator  consists  of  a  verti- 
cal cylindrical  vessel  with  a  gas  exit  in  its  cover;  the  inflow  of 


3o 


ELECTROLYSIS   OF   WATER. 


water  through  W  is  so  controlled  that  the  gas  separator  is 
filled  with  water  above  the  entrance  of  the  gas  tube. 
The  gases  ascend  into  the  gas  separator  carrying  with  them 
their  water  spray,  leaving  the  latter  in  this  vessel.  At  the 
same  time  the  water  flows  out  of  the  gas  separator  through 
the  down-take  tube  into  the  connecting  water  channels.  The 
branch  connection  a  serves  for  emptying  the  apparatus. 

Schmidt  has  therefore   taken  up  the  bipolar  arrangement 


fig.  19. 

for  electrolytic  decomposition  of  water  as  proposed  by  Latch- 
inoff,  and  made  it  technically  applicable  by  the  filter-press- 
like  construction.  This  construction  gives  also  the  advantage 
of  a  small  floor  space  as  well  as  economy  in  insulation,  wire 
connections  and  gas  exit  tubing. 

A  perspective  view  of  a  Schmidt  electrolyzer  is  shown   in 
Fig.  19. 

FORM    OF   APPARATUS. 

In    the  apparatus,    Schmidt   uses   asbestos  cloth   for    dia- 
phragms, reinforced  with  rubber  on  the  edges  for  the  purpose 


PROCESS   OF  SCHMIDT. 


33 


TABLE  IV.     FOR  1 10  VOLTS. 


V 



itnber  ol 
ambers. 

stinction 

mperes. 

lowatts. 

Litres  per  hour. 

Cubic  metres 
per  twenty- 
four  hours. 

a* 
g'§S 

||| 

|i 

fco 

Q 

* 

M         H           0 

H           0 

|s 

s  I2 

£3 

44 

B    15 
B    30 
B    60 

15 

^0 

60 

1.65 

275 
550 
IIOO 

137 
275 
550 

6.6 
13-2 

26.4 

11 

13.2 

100 
200 
500 

£ 

700 
2500 
4200 

B  100 

100 

11.00 

1850 

925 

44.4 

22.2 

800 

i/4 

7500 

B  150 

150 

16.50 

2750 

1375 

66.0 

33-0 

1200 

i# 

14000 

ARRANGEMENT. 

Fig.  20  shows  the  arrangement  of  the  Schmidt  plant. 
The  main  conductors  pass  over  a  small  switchboard  provided 
with  lead  fuses,  ampere  metre,  and  a  small  regulating  rheo- 
stat which  may  be  switched  in  and  out  of  the  circuit.  The 
contents  of  the  apparatus  may  be  let  out  in  a  basin  into  which 
the  distilled  water  needed  for  refilling  is  also  introduced.  The 
filling  and  supplying  are  provided  for  by  a  small  hand-pump. 

Pressure  gauges  are  provided  on  the  gas-conducting  pipes 
before  they  branch  off  into  the  gasometers. 

RULES   FOR   OPERATING. 

Schmidt  has  given  out  a  series  of  articles  upon  the  construc- 
tion and  operation  of  his  apparatus  which  are  here  reproduced, 
because,  with  the  exception  of  the  after  data  relating  to  the 
special  construction  of  his  apparatus,  they  will  serve  as  general 
information  for  the  other  processes  for  the  electrolytic  decom- 
position of  water. 

(a)  GASOMETER. 

The  gasometers  should  never  be  set  up  in  the  same  room  in 
which  the  persons  work  or  which  is  used  as  a  thoroughfare  by 
the  employees,  and  are  always  to  be  erected  in  an  open  space 
which  is  at  a  considerable  distance  from  occupied  rooms  and 
work  places. 

It  is  best  for  the  gasometers  to  stand  entirely  isolated,  and 
access  to  trespassers  prevented  by  a  suitable  fence. 


32  ELECTROLYSIS   OF   WATER. 

at  Bochum,  99.8  per  cent,  oxygen,  o.i  per  cent,  carbonic  acid 
and  o.i  per  cent,  nitrogen.1 

TYPES  OF  APPARATUS. 

Schmidt  builds  two  series  of  apparatus  types  for  better 
adaptation  to  existing  lighting  circuits  with  direct  current,  i.  e.y 
for  the  usual  tensions  of  65  and  no  volts. 


The  normal  sizes  of  such  apparatus  are  given  in  tables  III 
and  IV  : 

TABUS  III.    FOR  65  Voi/rs. 


"Sa 

g 

*o  ^  . 

s  «' 

|| 

1 
i 

I 
t 

±! 

i 

litres  per  hour. 

Cubic  metres 
per  twenty- 
four  hours. 

I'll 

Q,  D.JS 

& 

-1 

•CJ2 

** 

Q 

< 

M 

H           O 

H            O 

I8 

Q  ='~ 

26 

B    15 

15 

0.975 

163 

81 

3-90 

1-95 

60 

H 

500 

B    30 
B    60 

30 
60 

1-950 
3.900 

325 
650 

162 
325 

7.82 
15.64 

3-91 
7.82 

120 
250 

\x 

1750 
2700 

B  loo 

IOO 

6.500 

1085 

542 

2592 

12.96 

4OO 

l% 

5300 

B  150 

150 

9-750 

1630 

«i5 

39.10 

J9-55 

750 

11/4 

IOOOO 

Private  communication  to  the  author. 


PROCESS   OF  SCHMIDT. 
TABI,E  IV.     FOR  1 10  Voi/rs. 


33 


i 

u 

Number  oi 
chambers. 

Distinction 

Amperes. 

Kilowatts. 

litres  per  hour. 
H             O 

Cubic  metres 
per  twenty- 
four  hours. 

H           0 

Approximal 
capacity  in 
litres. 

Il| 
IP 

5  1'2 

Weight  in 
kilograms. 

44 

B    15 

15 

1.65 

275 

137 

6.6 

3-3 

IOO 

* 

700 

B    30 

•*o 

3-30 

550 

275 

I3.2 

6.6 

2OO 

I 

2500 

B    60 

60 

6.60 

I  IOO 

550 

26.4 

13.2 

500 

*x 

4200 

B  loo 

IOO 

11.00 

1850 

925 

44-4 

22.2 

800 

1% 

7500 

B  150 

150 

16.50 

2750 

1375 

66.0 

33-0 

1200 

1% 

14000 

ARRANGEMENT. 

Fig.  20  shows  the  arrangement  of  the  Schmidt  plant. 
The  main  conductors  pass  over  a  small  switchboard  provided 
with  lead  fuses,  ampere  metre,  and  a  small  regulating  rheo- 
stat which  may  be  switched  in  and  out  of  the  circuit.  The 
contents  of  the  apparatus  may  be  let  out  in  a  basin  into  which 
the  distilled  water  needed  for  refilling  is  also  introduced.  The 
filling  and  supplying  are  provided  for  by  a  small  hand-pump. 

Pressure  gauges  are  provided  on  the  gas-conducting  pipes 
before  they  branch  off  into  the  gasometers. 

RULES   FOR   OPERATING. 

Schmidt  has  given  out  a  series  of  articles  upon  the  construc- 
tion and  operation  of  his  apparatus  which  are  here  reproduced, 
because,  with  the  exception  of  the  after  data  relating  to  the 
special  construction  of  his  apparatus,  they  will  serve  as  general 
information  for  the  other  processes  for  the  electrolytic  decom- 
position of  water. 

(a)  GASOMETER. 

The  gasometers  should  never  be  set  up  in  the  same  room  in 
which  the  persons  work  or  which  is  used  as  a  thoroughfare  by 
the  employees,  and  are  always  to  be  erected  in  an  open  space 
which  is  at  a  considerable  distance  from  occupied  rooms  and 
work  places. 

It  is  best  for  the  gasometers  to  stand  entirely  isolated,  and 
access  to  trespassers  prevented  by  a  suitable  fence. 


34  ELECTROLYSIS   OF   WATER. 

In  locations  in  which  strong  winds  or  frost  are  to  be  ex- 
pected the  gasometers  must  be  under  cover,  which  latter  must 
be  constructed  as  light  as  possible  and  is  best  covered  with 
roofing  paper.  The  side  walls  of  the  building  may  be  built 
of  masonry. 

No  stones,  pieces  of  metal  or  other  solid  bodies  must  be 
used  for  weighing  down  the  holders.  It  is  much  more  to  be 
recommended  to  load  up  the  bell  by  the  use  of  fine  gravel  or 
water. 

The  gasometers  are  to  be  so  arranged  that  the  bells,  in  or- 
der that  they  may  be  completely  emptied,  can  sink  entirely 
into  the  basin. 

(*)  CONDUCTORS  AND  WATER  SUPPLY. 

The  supply  pipes  may  be  iron  or  lead  tubes.  The  latter 
metal  must  always  be  used  where  corrosion  of  the  pipes  by 
moisture,  acids  or  other  vapors  is  to  be  feared. 

The  conductors  may  be  carried  on  the  walls  of  the  build- 
ings like  gas  pipes,  through  the  air,  or  let  into  the  ground, 
yet  care  must  be  taken  that  the  lowest  points  are  provided 
with  sinks,  having  drainage  coils  for  the  purpose  of  removing 
condensed  water. 

A  very  careful  fitting  of  the  same  is  necessary  on  account 
of  the  small  weight  and  great  capacity  of  the  hydrogen  for 
diffusion. 

The  arrangement  of  the  conducting  pipes  is  under  all  con- 
ditions to  be  such,  that  two  systems  of  piping  lead  from  the 
gas-generating  plant  directly  to  the  gasometers.  The  branch 
pipes  for  leading  off  the  gases  to  where  they  are  used  is  to  be 
connected  to  these  conductors  at  only  one  place  in  each. 

Just  back  of  the  branching  off  a  water  seal  must  be  placed, 
such  as  a  water-bottle,  in  order  to  prevent  any  ignition  of  the 
gas  in  the  distributing  pipes  by  a  communication  backwards 
to  the  contents  of  the  gasometer. 

These  water  seals  prevent,  also,  the  escape  of  the  gas  from 
one  gasometer  into  the  other  if  by  carelessness  a  connection 


PROCESS  OF  SCHMIDT.  35 

has  been  left  between  the  distributing  pipes,  and  the  pressure 
in  the  two  gasometers  may  be  unequal. 

(c)  MEASURING  AND  CONTROLLING  APPARATUS. 

Just  back  of  the  connections  of  the  generator  to  the  con- 
ductors leading  off  the  gas  to  the  gasometers,  cocks  must  be 
placed. 

(a)  The  pressure  guage.  This  consists  of  a  U-shaped,  bent 
glass  tube  which  is  half  filled  with  colored  water  and  has  a 
millimeter  scale  attached. 

Care  must  be  exercised  that  the  pressure  in ,  the  two  side 
conducting  pipes  is  always  kept  the  same. 

(6)  The  controlling  apparatus. — This  consists  of  two  small, 
thin  glass,  water-bottles  with  metal  bases.  The  exit  points 
are  of  metal  with  a  wide  bore ;  they  stand  very  nearly  oppo- 
site to  each  other.  A  small  quantity  of  gas  escapes  constantly 
from  them,  which  is  kept  ignited. 

If  a  mixture  of  gas  enters  them,  the  contents  of  the  flask 
ignite  instantly  and  the  demolition  of  them  gives  notice  at 
once  of  the  dangerous  condition  existing. 

(d)  COCKS  AND  JOINTS. 

The  cocks  used  should  be  only  of  the  best  material  (bronze) 
and  very  carefully  ground  in. 

It  is  a  particular  characteristic  of  pure  oxygen  that  when 
in  a  moist  condition  it  attacks  metals  much  stronger  and 
quicker  than  air,  and  the  cocks  must,  therefore,  be  tested 
more  frequently  as  to  their  condition  than  otherwise  neces- 
sary. 

All  joints  are  to  be  made  carefully  with  asbestos,  avoiding 
rubber  and  other  combustible  substances. 

(e)  GAS  PRESSURE. 

The  gas  pressure  can  be  chosen  according  to  the  wished-for 
purposes,  but  care  must  be  taken  that  it  is  sufficiently  high  to 
overcome  the  back  pressure  in  the  water  seals. 

The  advice  to  keep  the  pressure  equal  in  both  conductors 
is  only  necessarily  observed  when  both  gases  are  utilized. 


36  ELECTROLYSIS   OF   WATER. 

If  one  gas  is  left  to  escape,  the  pressure  in  this  conductor  is 
kept  somewhat  smaller  to  insure  greater  security. 

(/•)  BURNER. 

Although  it  is  possible  to  lead  both  gases  through  a  hose 
to  the  blowpipe,  by  using  an  ordinary  T  connection  provided 
with  cocks,  yet  there  is  in  such  apparatus  some  certain  dan- 
ger of  the  flame  striking  back,  which  may  be  caused  by  a 
kinking  of  the  hose  or  by  some  one  carelessly  treading  upon 
the  tube. 

It  is  therefore  recommended  to  use  only  such  blowpipes  in 
which  both  gases  are  brought  to  the  mixing  point  in  sepa- 
rate pipes,  and  these  connected  with  the  point  of  the  branch 
pipe  by  a  reinforced  tube. 

To  avoid  with  certainty  the  striking  back  of  the  flame  it  is 
necessary  that  the  current  of  gas  have  a  certain  minimum 
velocity  in  the  point  of  the  burner.  Since  the  gas  pressure  is 
constant,  the  burner  point  must  have  different-sized  openings 
according  to  the  sizes  of  the  flame  to  be  used. 

The  introduction  of  tubes  with  wire  mesh  partitions  is  not 
a  sure  protection,  since  the  wire  gauge  is  in  many  cases  trav- 
ersed by  the  flame. 

The  gas  pressure  is  so  chosen  that  it  is  large  enough  for 
the  largest-sized  burners.  With  a  blowpipe  point  of  i  mm. 
diameter  the  gas  pressure  must  be  at  least  200  mm.  of  wafer. 

The  starting  of  the  burner  must  always  be  done  by  first 
turning  on  the  hydrogen  cock  and  igniting  the  gas  ;  only  then 
is  the  oxygen  cock  to  be  opened  with  care,  until  the  required 
mixture  has  been  obtained.  In  putting  out  the  flame  a  re- 
verse order  is  to  be  followed — oxygen  is  first  turned  off  and 
afterwards  the  hydrogen,  otherwise  the  flame  is  very  apt  to 
strike  back.  Mixing  cocks  are  very  much  to  be  preferred 
which  possess  a  plug  with  double  boring,  moved  by  a  spring, 
by  which  the  opening  up  and  shutting  off  of  the  gases  must 
take  place  in  the  right  order. 


PROCESS  OF  SCHMIDT.  37 

(£•)  SETTING  UP  OF  THE  APPARATUS. 

In  setting  up  the  apparatus  special  care  must  be  taken  that 
the  passages  are  carefully  cleaned  out  and  do  not  contain  for- 
eign matter. 

The  diaphragms  must  be  put  in  place  with  particular  care 
so  that  the  sides  provided  with  rubber  are  towards  the  negative 
electrode  surfaces,  at  which  the  hydrogen  gas  is  evolved. 
Care  must  also  be  taken  that  no  moving  of  the  holes  from  the 
perforations  in  the  plates  takes  place,  which  would  result  in 
narrowing  the  passages. 

The  work  of  setting  up  can  be  made  easier  by  loosely 
screwing  up  the  lugs  and  passing  through  them  a  suitable  rod. 

The  apparatus  must  be  well  insulated  from  the  earth  and 
also  have  no  metallic  connections  with  the  gas  pipes  ;  tests 
must  be  made  to  see  that  the  insulation  in  the  apparatus  itself 
is  in  good  condition. 

(h)  CHARGING. 

The  charge  of  the  apparatus  is  a  10  per  cent,  solution  of 
pure  refined  potassium  carbonate  (pearl  ash)  in  distilled  water, 
of  specific  gravity  i.ioo.  It  must  contain  no  appreciable 
amount  of  mineral  acids  or  chlorine. 

(*)  STARTING  UP. 

Before  the  apparatus  is  filled  and  closed,  the  gas  pipes,  gas- 
ometers and  the  cocks  are  to  be  tested  for  their  tightness  in 
the  usual  manner.  The  gasometers  must  be  quite  empty. 

After  the  apparatus  has  been  filled  it  should  work  for  a  short 
time  with  the  pipes  branching  from  the  gas  pipes  open,  and 
connection  with  the  gas  pipes  only  made  when  the  solution 
has  stopped  foaming  or  the  latter  has  moderated  greatly. 

Care  must  be  taken  that  no  great  difference  of  pressure 
arises  in  the  two  gas  conductors. 

After  tests  have  been  made  on  the  escaping  gases  and  their 
purity  has  been  proven,  the  gasometers  may  be  connected  up 
and  commence  to  be  filled.  (The  purity  of  the  gas  is  best 
tested  by  leading  a  little  of  it  through  a  rubber  tube  into  a 


38  ELECTROLYSIS   OF   WATER. 

test-tube  entirely  filled  with  water  and  when  the  latter  is 
filled  with  gas,  close  the  end  with  the  thumb,  and  bring  it  near 
a  flame.  The  hydrogen  should  burn  quietly  and  the  oxygen 
should  not  ignite.) 

(k)  OPERATION. 

The  height  of  the  liquid  in  the  gas  separators  must  always 
be  kept  in  view  since  it  is  absolutely  necessary  that  the 
chambers  of  the  electrolyzer  be  always  filled  with  the  fluid  and 
the  collection  of  gas  in  them  prevented. 

The  apparatus  decomposes  134  cubic  centimetres  of  water 
per  kilowatt  hour  and  this  quantity  must  be  replaced. 

The  replacement  must  be  done  by  means  of  distilled  water. 
Should  the  solution  foam  very  strongly  at  the  start,  some 
petroleum  can  be  poured  into  the  gas  separator. 

The  apparatus  must  be  taken  apart  every  four  weeks  and 
cleaned  ;  the  electrolyte  can  be  used  over. 

If  the  apparatus  takes  too  much  or  too  little  current,  the 
voltage  between  the  single  plates  or  electrodes  is  to  be  tested 
by  a  voltmeter.  If  the  chamber  shows  no  tension,  or  only 
very  little,  it  indicates  that  a  short  circuit  has  taken  place 
through  the  metallic  portions  of  the  two  electrodes ;  if  the 
tension  is  extremely  high,  it  indicates  a  complete  or  partial 
emptying  of  the  chambers  by  reason  of  the  stopping  up  of  the 
exit  channels. 

In  both  cases  the  apparatus  must  be  taken  apart  and  given 
a  thorough  cleaning. 

It  is  recommended  that  the  apparatus  be  cut  out  of  the  cir- 
cuit as  seldom  as  possible ;  at  times  of  small  gas  requirement, 
and  over  night,  it  is  left  working,  when  practicable,  with  a 
quite  small  current. 

If  after  long  use  of  the  apparatus  it  appears  that  some  of 
the  electrode  surfaces  at  which  the  oxygen  is  being  evolved 
show  a  strong  oxide  covering,  and  the  chambers  will  let 
through  no  more  current,  the  condition  may  be  remedied  by 
changing  the  poles  of  the  apparatus.  This  operation  is 


PROCESS  OF  SCHMIDT.  39 

to  be  done  only  with  the  greatest  care,  and  the  apparatus  is  not 
to  be  connected  to  the  reversed  conductors  until  it  is  furnish- 
ing quite  pure  gas. 

COST  OF  PLANT  FOR  THE  SALE  OF  COMPRESSED  GAS. 

The  cost  of  a  plant  of  this  system  for  the  daily  production 
of  33  metres  of  oxygen  and  66  metres  of  hydrogen  per  twenty- 
four  hours  is  calculated  by  Schmidt1  in  the  following  manner. 

Site  of  1200  square  metres $      250.00 

Building,  150  square  metres  under  roof 2,000.00 

Office  and  dwelling  100  square  metres,  two  stories 3,000.00 

Boiler,   30  sq.  metres  h't'g  surf,  with  foundation  and  chimney  1,250.00 

Steam  engine,  with  foundation  and  pipe  connections 1,625.00 

Dynamo,  15.5  kilowatts 412.50 

Switchboard  with  instruments 100.00 

Decomposition  cell  of  16.5  kilowatts  capacity 2,400.00 

Accessories,  tubing  and  wire  conductors,  heating  and  lighting 1,250.00 

Gasometer  for  20  cubic  metres  of  oxygen,  set  up 600.00 

Gasometer  for  40  cubic  metres  of  hydrogen,  set  up 875.00 

Gas  compressor,  capacity  50  cubic  metres  of  oxygen  per  10  hours  625.00 

Gas  compressor,  capacity  100  cubic  metres  of  hydrogen  in  TO  hours  1,000.00 

Miscellaneous,  pipe  connections,  emptying  arrangements,  etc....  150.00 

Belting,  shafting 250.00 

Furnishings 375-OO 

Erection,  freight,  pipe  coverings 500.00 

looo  steel  cylinders,  at  $10.00 10,000.00 

Extras  and  starting  up 1,787.50 

Total $27,500.00 

The  cost  of  running  and  the  profits  of  such  a  plant  are  cal- 
culated by  Schmidt  :' 

COST  OF  OPERATION  FOR  THE  SALE  OF  COMPRESSED   GAS. 

Power.     25  H.  P.  for  the  decomposition  of  water. 

5  H.  P.  for  the  compression  during  the  day. 

30  H.  P.  total. 

Coal    1.5  kg.  per  H.  P. -hour  for  300  days  of  24  hours  each  =  330 

metric  tons,  at  $3.75  per  ton $  1,250.00 

I  Superintendent 1,000.00 

1  Private  communication  to  the  author. 


4O  ELECTROLYSIS   OP   WATER. 

Brought  forward $2,250.00 

I  Workman 625.00 

3  Machinists i  ,050.00 

Lubricants,  waste  and  commutator  brushes 500.00 

5  per  cent,  interest  on  the  cost  of  the  plant i  ,375.00 

10  per  cent,  sinking  fund 2,750.00 

Heating,  lighting,  water 150.00 

Bxtras  and  repairs 425.00 

Total $  9, 125.00 

At  the  present  average  selling  price  of  $i  per  cubic  metre 
for  oxygen  and  31^  cents  per  cubic  metre  for  hydrogen, 
allowing  a  10  per  cent,  loss  of  gas,  the  income  would  be  : 

9000  cubic  metres  of  oxygen,  at  |i .00 $  9,000. oo 

18,000  cubic  metres  of  hydrogen,  at3i^  cents 5,625.00 


Total   |[4,625.oo 

Royalties,  10  per  cent.,  about 1,500.00 

$13,125.00 
Profit  from  sale  of  flasks 375-OO 

$13,500.00 
Operating  expenses 9,125.00 

Profit $  4,375.00 

Allowing  about  16  per  cent,  extra  dividends. 

In  the  above,  assumptions  are  made  that  both  gases  are  sold 
in  the  compressed  condition  ;  the  cost  is  33^  cents  per  cubic 
metre.  It  can  plainly  be  seen  that  the  oxygen  determines  the 
condition  for  a  profitable  operation  of  the  plant. 

The  figures  work  out  naturally  much  more  favorably  if 
the  gases  are  used  on  the  spot,  where  no  compression  plant  is 
necessary. 

When  the  power  needed  can  be  taken  from  an  already  exist- 
ing electrical  plant,  and  in  consequence  of  being  part  of  a 
work  already  in  operation,  no  particular  clerical  force  being 
necessary,  the  figures  are  more  favorable. 

COST  OF  OPERATION  WITHOUT  COMPRESSION. 

It  is  therefore  worth  while  to  work  out  separately,  for  the 
three  possible  cases  of  producing  gas,  the  cost  of  maintenance, 
in  doing  which  we  will  assume  the  extreme  cases  in  the  cost 
of  power,  namely  %  and  i  ^  cents  per  kilowatt  hours. 

The  figures  are  as  follows : 


PROCESS  OF  SCHMIDT.  41 

(a)  FOR  DETONATING  GAS. 

Production  of  Both  Gases,  i.  <?.,  of  Detonating  Gas. 

The  cost  of  plant  is  lowered  in  consequence  of  the  smaller 
space  occupied,  the  omission  of  the  power  and  current  plant, 
the  compressors,  the  office  and  dwelling  and  the  supply  of 
gas  containers,  to  the  extent  of  about  $7125.00. 

The  yearly  cost  of  running  would,  therefore,  be  as  follows 
for  the  respective  costs  of  power  per  kilowatt  hour : 

J^  cent.  i  YI  cents. 
16.5  kilowatt  X  24  hours  X  360  days  =  142,560  kilowatt 

hours $356.25  $1781.25 

i  workman 350.00  350.00 

Supplies,   etc 250.00  250.00 

5  per  cent,  interest  on  cost  of  plant 35T-25  35r-25 

10  per  cent,  sinking  fund 712.50  712.50 

Heating,  lighting,  water,  repairs,  etc 100.00  100.00 

Total $2125.00        $3550.00 

The  total  cost  of  a  cubic  metre  of  detonating  gas  with  a 
yearly  production  of  27,000  cubic  metres  is,  therefore,  7^ 
-13%^  cents  per  cubic  metre. 

(*)  FOR  OXYGEN. 

Utilization  of  Oxygen  Alone. 

As  compared  with  the  cost  of  plant  in  # ,  there  is  a  reduction 
in  the  capital  invested  to  the  extent  of  the  hydrogen  gasometer 
with  its  appendages,  so  that  it  will  be  about  $6250.00. 

The  cost  of  operation  amounts  to : 

y±  cent  per  kilo-  \Y4  cents  per  kilo- 

watt hour.  watt  hour. 

Power $356.25  $1781.25 

i  workman 350  oo  350.00 

Supplies,  etc 250.00  250.00 

5  per  cent,    interest 312.50  312.50 

10  per  cent,  sinking  fund 625.00  625.00 

Not  specified 100.00  100.00 

Total .••••$1993-75  $3418.75 

The  total  cost  per  cubic  metre  of  oxygen,  with  the  yearly 
production  of  9,000  cubic  metres  is,  therefore,  22-38  cents 
per  cubic  metre. 


42 


ELECTROLYSIS   OF   WATER. 


(c)  FOR  HYDROGEN. 

Utilization  of  the  Hydrogen  Alone. 

As  compared  with  #,  the  oxygen  gasometer  is  spared,  and 
the  cost  of  the  plant  will  be  approximately  $6500.00. 
The  cost  of  running  will  be : 

y±  cent  per  1%  cents  per 

kilowatt  hour.  kilowatt  hour. 

Power $365-25  $r?8i.25 

i  workman 350.00  350.00 

Supplies,  etc 250.00  250.00 

5  per  cent,    interest 325.00  325.00 

10  per  cent,  sinking  fund 650.00  650.00 

Not  specified 100.00  100.00 


Total $2031.25  $3456.25 

The  total  cost  per  cubic  metre  of  hydrogen,  with  a  yearly 
production  of  18,000  cubic  metres,  must  be  11^-19^  cents 
per  cubic  metre. 

PRACTICE. 

The  Schmidt  arrangement  is  especially  suited  for  small  op- 
erations since  it  is  easily  adapted  to  existing  direct  current 
lighting  plants.  In  consequence  the  apparatus  has  been  in- 
troduced in  a  relatively  short  time  in  many  accumulator 
works  for  soldering  purposes.  At  present  the  following  plants 
are  in  operation  furnished  with  Schmidt  apparatus  : 

V. 


No. 

Plant. 

Erected. 

Volt- 
age 

Am- 
peres. 

I 
2 

3 

4 

8 
9 

10 

ii 

1 

Accumulatorenfabrik  Oerlikon  

June,             1898 
March,          1899 
January,       1900 
March,          1900 
fuly,              1900 
August,         1900 
September,  1900 
[anuary,       1901 
May,              1901 
[une,             1901 
September,  1901 

65 
no 
no 

70 

no 
70 
no 
no 
220 
65 

IIO 

15 
1  60 

15 
30 
15 
60 
60 
30 
30 
30 
30 

Rheinisches  Stahlwerk  

Henry  Tudor,  Rosport,  Luxemburg  
Soc.  Espanola  del  Ace.  Tudor,  Zaragoza... 
Elektroch.  Institut  des  Polyt.  Zurich  
The  Tudor  Accum.  Co.,  Ltd.  Manchester 
Soc.  fransaise  de  1'Acc.  Tudor,  Lille  
Societe  Tudor  Bruxelles  

Fabrik  elektrochem.  Produkte,  Wetzikon 
Accumulat.-Fabr.  Oerlikon,  Enlargement 
Soc.  ital.del  Carburo  di  Calcio,  Terni  

The  manufacture  and  the  introduction  of  the  Schmidt 
Water-electrolyzer  has  been  undertaken  by  the  Machinenfab- 
rick  Oerlikon  of  Zurich,  Switzerland. 


RITTER'S  APPARATUS. 


43 


(b)  With  Complete  Non-Conducting  Partitions. 
(a)  For  Instruction  and  Laboratory  Apparatus. 

A  demonstration  apparatus  for  the  electrolysis  of  water  us- 
ing complete  non-conducting  partitions,  and  which  separates 
the  gas  evolved,  is  used  particularly  for  lecture  purposes,  in 
order  to  show  clearly  that  water  consists  of  two  volumes  of 
hydrogen  combined  with  one  volume  of  oxygen. 

RITTER'S  APPARATUS. 

As  Ostwald1  incisively  remarked,  we  find  the  "  prototype 
of  the  present  widely  used  forms  of  apparatus,"  in  the  arrange- 
ment shown  more  than  a  century  ago  by  Ritter2,  two  of  whose 
best  apparatus  are  reproduced  in  Figs.  21  and  22,  for  the  pur- 
pose of  comparison. 

In  this  group  of  apparatus,  intended  especially  for  purposes 


Fig.  21. 


Fig.  22. 


of  instruction,  the  conductivity  of  the  water  to  be  decomposed 
is  increased  by  additions.  Usually  an  8-10  per  cent,  solution 
of  sulphuric  acid  is  employed. 

1  Ostwald  :  Elektrochemie,  ihre  Geschichte  und  Lehre,  1890,  p.  162. 

*  Voigt's  Magazin  fiir  den  neuesten  Zustand  der  Naturkunde,  2,  356, 
1800. 


44 


ELECTROLYSIS   OF   WATER. 


FORMS  OF  THE  APPARATUS. 

One  of  the  simplest  apparatus  which  is  yet  in  use  is  shown 
in  Fig.  23*.     Two  platinum  wires  pass  through   the  neck   of 


the  vessel  #,  ending  in  platinum  poles,  one  connected  with  the 
-f  pole  and  the  other  with  the  —  pole  of  a  galvanic  battery. 
The  quantities  of  gas  evolved  can  be  read  off  on  a  graduated 
glass  tube  not  far  above  the  electrodes.  The  tubes  are  natur- 
ally filled  with  electrolyte  before  the  current  is  turned  on. 
Since  oxygen  is  more  soluble  in  the  electrolyte  than  hydro- 
gen, and  since  a  small  quantity  of  ozone  always  forms  at  the 
-J-  pole,  there  is  obtained  under  the  usual  conditions  some- 
what less  than  one  volume  of  oxygen  to  two  volumes  of  hy- 
drogen. The  formation  of  ozone  is  diminished  by  heating  the 

1  Graham-Otto:  Lehrbuch  der  Chemie,  II,  i,  146. 


HOFMANN'S  APPARATUS. 


45 


water,  and  a  more  correct  relation  between  the  gas  volumes  is 
thus  obtained. 

HOFMANN'S  APPARATUS. 

The  forms  of  apparatus  most  in  use  are  based  upon  the  con- 
struction described  by  A.  W.  Hofmann.  One  of  the  newest 
forms  is  that  pictured  in  Fig.  24. 

The  apparatus  consists  of  a  U-tube  for  the  reception  of  the 
electrolyte  (acid  or  alkaline  water).  The  arms  of  the  same  are 
somewhat  long  and  are  closed  above  with  stop-cocks.  Plati- 
num wires  are  melted  into  the 
lower  part  of  the  arms  and 
carry  the  sheet  platinum 
electrodes.  The  fluid  forced 
out  by  the  evolution  of  gas 
passes  through  a  rubber  tube 
into  an  adjustable  reservoir. 
If  the  current  is  allowed  to 
pass  some  time  the  gas  vol- 
umes can  be  easily  read  off, 
and  by  letting  them  escape 
through  the  stop-cocks  each 
can  be  recognized  by  its 
characteristic  reactions. 
Likewise  the  presence  of 
ozone  may  be  determined 
when  using  acidulated  water 
at  low  temperatures. 

The  apparatus  has  the  ad- 
vantage that  the  influence  of 


Fig.  24. 


the  absorption  of  the  electrolyte  may  be  avoided  by  running 
the  apparatus  some  time  before  closing  the  stop-cocks,  and  the 
gas  can  be  brought  up  to  any  desired  pressure  by  raising  the 
reservoir. 

The  improvements  of  the  Hofmann  Electrolyzer  consisting 
in  a  device  for  preventing  overflow,  and  the  use  of  exchange- 


46 


ELECTROLYSIS   OF   WATER. 


able  glass  caps  on  the  platinum  electrodes  has  been  patented 
by  Geissler  &  Co.,  of  Berlin,  in  the  German  patent  157,840  of 
the  6th  of  June,  1901. 

If  it  is  desired  to  produce  a  gas  especially  rich  in  ozone  for 
purposes  of  demonstration,  the  concentration  of  the  sulphuric 
acid  used  is  increased,  taking  one  volume  of  concentrated  sul- 
phuric acid  to  five  or 
six  volumes  of  water. 
The  current  density  is 
also  increased  by  using 
in  place  of  foil  fine 
wires  of  platinum  or 
platinum  iridium  as 
electrodes.  Finally  the 
temperature  of  the  elec- 
trolyte is  kept  as  low  as 
possible.  In  this  man- 
ner, for  instance,  Soret1 
obtained  at  a  tempera- 
ture of  5-6°  C.  3  per 
cent,  of  ozone,  and  by 
cooling  with  ice  and 
salt  as  high  as  6  per  cent. 

BUFF'S  APPARATUS. 

An  apparatus  espe- 
cially designed  for  the 
manufacture  of  oxygen 
rich  in  ozone,  is  described  by  Buff.2  It  is  shown  in  Fig.  25, 
which  is  intelligible  without  further  description. 

ROSENFELD'S  APPARATUS. 

A   demonstration   apparatus,    which    can    be   constructed 
with  the  simplest  materials  and   with  all  the   parts  easily 

1  Poggendorf's  Annalen. 

2  Graham-Otto,  "Lehrbuch  der  Chemie,"  II,  I,  84. 


REBENSTORFF'S  APPARATUS. 


47 


replaceable,   devised  by   M.  Rosenfeld,  is  shown  in  Fig.  26.* 

This  consists  of  a  cylinder,  c,  7  cm.  high  and 
3  cm.  wide,  provided  with  two  well  fitting,  rub- 
ber stoppers,  the  upper  one  of  which  carries  two 
gas-collecting  tubes  70  cm.  high  and  i  cm.  in  di- 
ameter, provided  with  stop-cocks.  The  lower 
stopper  having  3  holes,  carries  the  2  electrodes 
and  the  glass  tube  r,  to  which  is  attached  by 
means  of  the  rubber  tube  ^,  a  funnel,  t.  The 
gas-collecting  tubes,  which  at  equal  heights 
must  possess  exactly  equal  volumes,  reach  down 
almost  to  the  lower  stopper,  while  the  smaller 
tube  r  projects  5  mm.  inside  the  cylinder.  The 
electrodes  are  about  6  cm.  higher  than  the  cylin- 
der. The  apparatus  allows  volumetric  investi- 
gations to  be  made  in  the  shortest  time  with  fee- 
ble currents.  Warming  of  the  electrolyte  is  to 
be  recommended  and  can  be  accomplished  by 
passing  a  gas  flame  around  the  tube. 

REBENSTORFF'S  APPARATUS. 

Rebenstorff2  has  proposed  to  use  the  Hofmann  principle  for 
decomposing  water,  as  a  voltameter.  In  this  case  the  filling 
funnel  must  be  connected  with  the  apparatus,  not  by  a  rubber 
tube,  but  by  a  glass  tube  firmly  fastened  to  the  U-tube,  as  was 
the  case  with  the  older  Hofmann  arrangement.  Two  marks 
are  then  placed  upon  the  funnel  tube,  and  the  time  is  measured 
in  which  it  takes  the  fluid  to  rise  in  this  funnel  tube  from  the 
lower  to  the  upper  mark,  in  consequence  of  the  evolution  of 
gas  in  the  U-tube.  The  placing  of  the  lower  mark  is  a  matter 
of  no  importance.  The  upper  mark  should  be  so  placed  that 
when  using  the  apparatus  as  a  voltameter  no  reduction  of  the 
volume  of  the  gas  to  normal  pressure  is  necessary  on  account 

1  Zeitschr.  phys.  und  chem.  Unterr.,  1900,  13,  261.     Chem.  Ztg.  Reper- 
torium,  1900,  43,  373. 

2  Zeitschr.  phys.  und  chem.  Unterr.,  1900,  13,  332.     Chem.  Ztg.  Reper- 
torium,  1900,  43,  373- 


48 


ELECTROLYSIS   OF   WATER. 


of  the  greater  density  of  the  sulphuric  acid.  This  is  the  case 
if  the  upper  mark  is  approximately  at  the  height  of  the  first 
one-third  of  the  difference  of  level  of  the  two  columns  of  liquid 
after  the  electrolysis  is  stopped.  If  the  marks  are  placed  in 
the  proper  manner,  it  only  remains  to  determine  the  volume 
of  gas  produced  during  the  rise  of  the  fluid  from  the  lower  to 
the  higher  mark.  Several  measurements  are  taken  and  the 
average  volume  found,  reduced  to  o°  C.  and  the  normal  barom- 
eter pressure,  correcting  for  the  tension  of  water  vapor. 

HABERMANN'S  APPARATUS. 

Habermann1  proposes  to  make  the  bell  of  the  latter  appa- 
ratus, shown  in  Fig.  27,  of  semi-cir- 
cular section  in  order  to  diminish  as 
far  as  possible  the  distance  of  the 
electrodes  apart.  He  obtains  with 
this  arrangement  a  very  consider- 
able decomposition  of  water  with  a 
thermal  element  of  fifty  couples,  es- 
pecially if  the  electrodes  reach  down 
nearly  to  the  lower  edge  of  the  gas 
bell.  The  gas  bells  B  are  contained 
in  a  vessel,  A,  and  are  fixed  thereto 
by  means  of  the  stopper  C.  The  bells 
terminate  above  in  round  tubes 
which  are  provided  with  two  tube 
connections  D  D.  The  bells  are  held 
fast  at  F  by  a  flat  piece  of  cork  and 
binding  twine. 

If  palladium  cathodes  are  used  in 
the  electrolysis  of  acidulated  water, 

Fig.  27 

we    observe,  according  to  Graham2, 

quite  considerable  quantities  of  hydrogen  and  fully  four  times 
as  much  when  using-  wire  cathodes  as  sheet  cathodes.  Glad- 


1  Zeitschr.  fur  ang.  Cheinie,  1892,  323-328. 

2  Compt.  rend.,  1869,  68, 101.     Pogg.  Ann.,  1869,  136,  317  und  1069. 


PROCESS   OF  ASCHERL.  49 

stone  and  Tribe  have  investigated  the  strong  reducing  quali- 
ties of  the  occluded  hydrogen. 

(b)  For  Technical  Purposes. 

The  fundamental  idea  underlying  the  demonstration  appa- 
ratus, that  is,  the  use  of  bells  of  non-conducting  material  cover- 
ing over  the  electrodes,  has  also  been  taken  advantage  of  by 
several  investigators  in  technical  apparatus,  but  without  much 
successful  application  in  practice. 

Process  of  Ascherl,  1894. 

E.  Ascherl  obtained  an  Austrian  patent  44/5862,  Nov.  9, 
1894,  dating  from  September  26,  1894,  for  an  "  Apparatus  for 
decomposing  water  by  means  of  dynamo  currents  and  for  the 
drawing  off  of  the  evolved  gases." 

PATENT    CLAIM. 

The  patent  claim  reads  : 

1.  "An   apparatus   for   the   decomposition  of   water   by 
means  of  dynamo  currents,  characterized  by  an  insulated  de- 
composition vessel,  #,  with  two  gas  bells,  b  &1 ',  beneath  which 
are  metallic  wire  brushes,  d,  connecting  with  the  necessary 
conducting  wires  of  the  dynamo  machine  and  which  may  be 
set  in  reciprocating  motion  by  a  shaft,  whereby  the  gas  col- 
lecting on  the  brushes  and  shaken  therefrom,  is  collected  by 
the  bells  and  led  away  by  the  collecting  tubes  g  and  h" 

2.  "  In  combination  with  the  apparatus  described  under  i, 
an  arrangement  for  drawing  off  of  the  gas  from  the  collect- 
ing reservoir,  consisting  of  the  receivers  k  k' ',  placed  in  water 
holders,  II' ,  and  communicating  on  one  side  with  the  collecting 
tubes  g  h,  and  on  the  other  side  in  connection  with  the  gas 
pumps,  so  that  by  the  sinking  of  water  previously  pumped 
into  the  receivers,  suction  is  produced  in  the  vessel  #." 

DESCRIPTION. 

In  the  adjacent  drawings,  Fig.  28  shows  the  apparatus  in 
section,  Fig.  29  in  plan,  and  Fig.  30  shows  a  front  view  of 
the  decomposing  apparatus. 


P:LECTROLYSIS  OF  WATER. 


Fig.  2S. 


Fig.  30. 


.      J (J      U         \  / 

r^u 


Fig. 


The  decomposing  apparatus  consists,  as  is  easily  seen  from 
the  drawings,  of  a  number  of  decomposing  vessels,  a,  filled  with 
acidulated  water,  made  of  wood  or  metal,  which  are  lined 
inside  for  better  insulation  with  glass  plates,  a'.  Two  glass 


PROCESS   OF   ASCHERL.  51 

bells,  b  and  b' ,  dip  into  each  of  these  vessels  and  are  fastened  to 
the  separators  c  and  covered  with  brushes  of  silver  or  platinum 
wires  d,  upon  which  the  gas,  formed  by  decomposition,  is  set 
free.  To  liberate  the  gas  generated  from  the  brushes  and  thus 
get  constant  action  of  the  current  and  quicker  decomposition 
of  the  water,  the  brushes  are  fastened  to  levers  e  made  of  hard 
rubber  and  which  are  capable  of  being  rotated  on  the  supports 
c,  and  given  a  quick  reciprocating  motion  by  means  of  the 
eccentric  f1-  on  a  shaft  /"driven  in  any  suitable  manner  by 
means  of  the  eccentric  rods/"2. 

The  strong  copper  wires  are  placed  in  the  lever  e  and  con- 
nected with  the  metallic  wire  brushes  and  serve  for  conduct- 
ing the  current.  The  -f  pole  of  the  dynamo  machine  being 
with  one  of  the  brushes  under  the  glass  bell  b  and  the  —  pole 
with  the  brush  under  the  bell  b' . 

The  decomposition  vessels  a  are  placed  upon  an  insulating 
foundation  n  (of  asphalt)  to  prevent  loss  of  current. 

As  soon  as  the  current  is  put  on,  decomposition  of  water 
takes  place  ;  to  keep  the  hydrogen  and  oxygen  accumulating 
in  the  gas  chambers  separated  from  each  other,  all  the  glass 
bells  b  are  connected  with  the  gas  collecting  tube  h,  and  all 
the  glass  bells  bf  with  the  collecting  tube  g. 

These  tubes  are  provided  with  the  regulating  valves^'  hf ',  and 
lead  to  the  reservoirs  k  or  k'  which  are  securely  placed  in  the 
open  water  containers  /  /',  with  which  they  are  in  communi- 
cation by  the  openings  m  near  the  bottom. 

The  receptacles  serve  for  sucking  off  the  gas  and  are  pro- 
vided with  the  water-gauges  0,  and  are  in  communication  with 
the  gas  pumps  by  the  tube  z,  while  the  containers  /  I'  are  fur- 
nished with  inlet  and  outlet  cocks.  When  the  gas  formed  in 
the  apparatus  and  collected  in  the  bells  b  b'  is  to  be  with- 
drawn, the  cocks  g'  h'  are  first  closed  and  the  receivers  k  k' 
put  in  communication  with  the  gas  pumps,  which  latter  con- 
vey the  gas  to  the  gasometers.  When  pumping  out  the 
reservoirs,  the  water  rises  in  the  same  nearly  to  the  top,  where- 
upon the  cocks  g'  h'  are  opened.  The  latter  thus  sink  into 

B  x  A  £*7"' 'v 
OF  THE 

UNIVERSITY  j 


52  ELECTROLYSIS   OF   WATER. 

the  receivers;  water  flows  into  them  and  exerts  a  suction 
upon  the  gases  which  are  coming  out  of  the  tubes  g  h.  By 
completely  letting  out  the  water  by  means  of  the  run-off  cocks 
of  the  holders  /  /',  the  reservoirs  k  k'  can  be  completely  rilled 
with  gas,  which  is  then  sucked  off  by  the  pumps  to  the  gas- 
ometers. 

In  the  author's  opinion,  the  whole  arrangement  contains  no 
new  principle  with  the  exception  of  the  motion  of  the  elec- 
trodes, for  purpose  of  diminishing  the  polarization.  If  the 
latter  purpose  is  to  be  achieved  by  mechanical  power,  how. 
ever,  many  other  means  of  doing  it  may  be  found  which  will 
obtain  it  in  a  simpler  manner.  The  proposed  use  of  silver 
as  electrode  material  is  not  permissible  with  acid  electrolytes. 

PRACTICE. 

The  apparatus  has  not  been  industrially  applied.  With  the 
exception  of  a  demonstration  apparatus  in  a  glass  works  in 
Bohemia,1  no  further  installation  has  been  made.  The  appa 
ratus  was  invented  for  supplying  the  oxyhydrogen  flame. 

The  process  of  the  Electricitat  Aktien-Gesellschaft,  for- 
merly Schuckert  &  Co.,  of  Nuremberg,  is  discussed  in  the 
division  A  (c),  although  it  works  with  partitions  of  non-con- 
ducting material,  since  in  other  respects  it  comes  nearest  to 
the  Garuti  apparatus. 

Process  of  Schoop,  19OO. 

The  recently  developed  construction  of  M.  U.  Schoop  may 
also  be  placed  in  this  group  of  apparatus.  The  German 
registered  design  for  the  same,  141,049,  of  September  5,  1900, 
contains  the  following  claim : 

PATENT  CLAIM. 

"Electrolytic  apparatus  for  the  decomposition  of  water 
characterized  by  solid  or  hollow  electrodes  of  sheet  lead  or 
steel  arranged  at  the  same  distance  from  the  base,  each  set  in 

1  Zeitschrift.  f.  Elektrot.,  Wien.,  1895,  551. 


PROCESS    OF    SCHOOP.  55 

a  glass   or  clay   tube    perforated    beneath    and   hermetically 
closed  above." 

It  is  easily  seen  from  Schoop's  final  patent  claim,  Austrian 
patent  1285  of  1900, what  he  regards  as  new  in  his  arrangement: 

1.  "  Electrolytic  apparatus  for  the  decomposition  of  water 
consisting  of  an  electrolyte  holder  acting  as  anode  whose  floor 
is  protected  from  contact  with  the  electrolyte  by  an  insulating 
covering,  and  a  number  of  tube-shaped  cathodes  resting  upon 
these   insulating  layers,   each   of   which   is  surrounded  by  a 
closed  glass  or  clay  tube  reaching  nearly  to  their  lower  ends, 
and  closed  above,  the  said  cathodes  being  perforated  at  their 
lower  free  ends  where  they  are  not  surrounded  by  the  enclo- 
sing tubes,  through  which  perforations  the  electrolyte  circu- 
lates freely,  and  through  which   the  gas  set  free  between  the 
insulating  tubes  and  the  cathode  tubes  passes  into  the  interior 
of  the  latter,   and  thence  through   conducting  tubes   to  the 
gasometer  or  other  places  where  used." 

2.  "An  altered  form    of  the  decomposition  apparatus  de- 
scribed in  i  in  which  instead  of  the  electrolyte  holders  acting 
as  cathodes,  cathodes  analogous  to   the  anodes  are  employed 
consisting  of  lead  tubes  surrounded  by  glass  or  clay  tubes 
which  permit  the  collection  of  the  hydrogen  in  the  same  man- 
ner as  designated  for  the  oxygen  under  claim  i." 

FORM  OF  APPARATUS. 

Fig.  31  shows  a  schematic  drawing  of  the  Schoop  apparatus. 
It  consists  of  two  decomposition  cells  united  with  each  other, 
each  containing  four  electrodes,  vis.,  two  anodes  and  two 
cathodes. 

The  tubular  electrodes  a  are  hung  in  enlargements  of  the 
glass  or  clay  tubes  c.  The  hermetical  sealing  of  the  electrodes 
in  the  surrounding  tubes  is  obtained  by  pouring  melted  mate- 
rial around  the  upper  end.  The  lower  part  of  the  tube  c  is 
perforated. 

The  electrode  tubes  a  are  perforated  half  way  up  and  filled 
inside  with  fine  lead  wires  in  order  that  the  evolution  of  gas. 


ELECTROLYSIS   OF   WATER. 


may  take  place  outside  as  well  as  inside  of  the  tube  with 
equal  intensity.  Besides  this  there  is  at  the  upper  end  of  the 
tubular  electrode  a,  a  passage  for  the  escape  of  the  gas.  The 
electrodes  are  connected  in  pairs  to  their  common  collecting 
tube  k.  This  connection  with  the  collecting  tube  is  effected 


"by  using  a  short  connecting  tube  of  non-conducting  material 
in  order  that  the  single  cells  may  be  insulated  from  each  other. 

Each  reservoir,  <?,  is  provided  with  a  water-gauge  for  observ- 
ing the  level  of  the  acid. 

From  the  preceding,  it  may  be  seen  that  Schoop  did  not 
carry  out  his  idea  described  in  his  patent  claim  of  the  Austrian 
patent,  namely,  that  of  using  a  vessel  as  anode  and  tubular 
-electrodes  as  cathodes,  while  the  bottom  of  the  vessel  was  in- 
sulated. This  arrangement  has  also  numerous  shortcomings. 

Leaving  out  of  consideration  that  the  utilization  of  the  elec- 
trodes, which  is  not  very  good  in  the  apparatus  in  general,  is 
not  improved  by  this  arrangement,  the  use  of  insulating  ma- 
terial in  the  electrolytic  apparatus  possesses  many  difficulties. 
It  is,  moreover,  difficult  to  find  an  insulating  material  (resin 
•or  solid  hydrocarbons)  which  possesses  a  constant  consistency 
at  all  temperatures  to  which  it  may  be  subjected.  If  cracks 


PROCESS  OF  SCHOOP.  55 

once  appear  in  this  insulation  at  the  bottom,  the  hydrogen  be- 
comes at  once  contaminated  with  oxygen.  On  the  other  hand^ 
with  the  arrangement  chosen  the  greatest  current  density 
would  be  expected  at  the  border  between  the  anode  vessel  and 
the  insulating  material.  Oxidation  of  the  organic  insulating 
material  would  follow,  as  has  been  observed  with  the  Schmidt 
apparatus  with  the  rubber  edges  of  the  asbestos  diaphragms, 
and  thus  unavoidable  contamination  of  the  oxygen  would  re- 
sult. 

Fig.  32*  shows  a  view  of  the  first  experimental  plant  with 


Fig.  32. 

which  Schoop  tested  his  system  on  a  large  scale.  Schoop 
claims  for  his  apparatus2  a  greater  security  in  operation  than 
in  any  of  the  systems  working  with  diaphragms,  a  perfect 
purity  of  the  gases,  and  ascribes  to  the  diaphragm  apparatus 
further,  the  disadvantage  that  with  even  small  variations  of 
density  in  the  diaphragms,  diffusion  can  occur  to  such  an  ex- 

1  From  an  original  photograph. 

2  Zeitschrift  f.  Elektrot.,  Wien,  1900,  37,  444.    Eclairage  electr.  (1900), 
21,  50.    Elektro-chem.  Zeitschrift,  igoo-'oi,  1O,  224. 


.56  ELECTROLYSIS   OF  WATER. 

tent  that  the  hydrogen  may  contain  up  to  the  danger  limit  of 
6  per  cent,  of  oxygen,  which  may  lead  to  explosions.  The 
resistance  of  the  apparatus  is  higher  than  in  other  systems.1 

The  gases  escape  under  about  one  metre  of  water  column. 
They  are  entirely  freed  from  acid  carried  over  by  passing 
them  through  milk  of  lime  before  entering  the  gasometer;  the 
apparatus  needs  to  be  taken  apart  only  after  several  months 
operation.  The  electrodes  are  said  not  to  be  attacked  ;  hard 
lead  is  recommended  as  the  best  material  for  them. 

OUTPUT. 

Schoop  gives  as  the  output  of  his  apparatus  68  litres  of 
oxygen,  and  136  litres  of  hydrogen  per  electrical  H.  P.  As- 
suming a  nearly  theoretical  current  output,  these  figures  would 
correspond  to  a  working  tension  of  2  j£  volts.  Since  Schoop 
says  at  one  place  when  using  lead  electrodes  with  acid  elec- 
trolyte an  electromotive  force  of  2.5  to  3.5  volts  per  appa- 
ratus may  suffice  for  creating  the  current  density,  it  may  be 
assumed  that  the  output  before  mentioned  applied  to  iron 
•electrodes  with  alkaline  electrolyte,  which  manner  of  work- 
ing is  also  described  by  Schoop  as  possible,  but  as  entailing 
a  high  cost  of  plant. 

COST  OF  OPERATION. 

Upon  these  figures  we  may  calculate  that  every  3  cubic 
metres  of  mixed  gas  requires  10.82  kilowatt  hours,  costing  at 
i^_!  i^  cents  per  kilowatt  hour  the  following : 

i  cubic  metre  of  detonating  gas 0.9  -  4.5    cents. 

i  cubic  metre  of  hydrogen I-2>5~  6.75 

i  cubic  metre  of  oxygen 2.70-13.50 

when  using  iron  electrodes. 

Using  acid  electrolyte  (sulphuric  acid  of  a  specific  gravity 
of  1.235)  and  lead  electrodes,  Schoop1  says,  from  the  data  ob- 
tained in  operating  a  plant  in  question,  that  a  voltage  of  3.9 
is  needed  with  cold  acid  and  3.6  with  warm  acid.  From  this 

1  Private  communication  to  the  author. 


PROCESS  OF  SCHOOP. 


57 


data,  assuming  a  theoretical  current  output  and  3.5  volts  to  be 
used,  there  is  required  18.67  kilowatt  hours  for  producing  3 
cubic  metres  of  mixed  gas,  and  the  cost  of  production  with 
power  at  ^  and  i  j{  cents  per  kilowatt  hour  is  respectively  : 

i  cubic  metre  of  detonating  gas I-55<>-  7- 750  cents. 

i  cubic  metre  of  hydrogen 2.325-14.625      " 

i  cubic  metre  of  oxygen 4.650-23.250      " 

PRACTICE, 

The  Schoop  water  decomposition  apparatus  was  tried  in  an 
experimental  plant  of  small  capacity  by  the  Cologne  Accumu- 
lator Works  of  G.  Hagen,  at  Kalk  on  the  Rhine,  and  this  firm 
erected  a  plant  for  a  total  daily  production  of  15  to  20  cubic 
metres  of  hydrogen  and  7.5  to  10  cubic  metres  of  oxygen. 


Fig-  33- 

The  plant  consisted  of  18  cells  connected  in  series,  through 
which  was  sent  150  to  200  amperes.  The  switchboard  con- 
tained: i  Weston  ammeter  for  250  amperes,  i  voltameter,  i 
indicator  of  the  direction  of  the  current,  i  low  current  cut  out, 
i  signal  bell,  and  2  water  manometers.  The  current  was  fur- 


58  ELECTROLYSIS   OF    WATER. 

nished  by  a  shunt-wound  dynamo  of  250  amperes  and  65  volts. 
The  primary  cost  of  the  plant  was  approximately  $1,250,  and 
the  operation  of  the  same  resulted  in  a  saving  of  $1,750  yearly, 
as  compared  with  the  previous  method  of  manufacture  of  hy- 
drogen for  soldering  purposes.  Fig.  33  shows  part  of  this 
plant. 

The  same  firm  has  undertaken  the  construction  of  the 
Schoop  apparatus  for  foreign  customers. 

Process  of  Hazard-Flamand,  1898. 

If  we  do  not  confine  ourselves  exclusively  to  the  electrolysis 
•of  water,  the  Hazard-Flamand  apparatus  may  be  classified 
with  this  group  of  apparatus.  It  was  patented  in  Germany, 
No.  106,499,  of  June  12,  iSgS.1 

FORM  OF  APPARATUS. 

The  inventor  describes  his  construction  as  a  "  water-sealed 
diaphragm  "  for  electrolytic  apparatus,  especially  for  the  elec- 
trolysis of  water.  The  principal  idea  of  the  diaphragm,  which 
is  intended  for  the  general  manufacture  of  gas,  and  which  pre- 
vents mixing  of  the  anode  and  cathode  fluids  saturated  with 
their  respective  gases,  is  shown  in  Figs.  34  and  35. 

In  the  box  A,  which  forms  the  cathode  and  is  provided  with 
ribs,  #,  for  increasing  the  lateral  surface  are  transverse  parti- 
tions, #',  cast  in  one  piece  with  the  box  A,  and  likewise  ribbed 
az  for  increasing  the  surface.  The  deep  gutter  B  is  filled  with 
an  insulating  fluid  and  receives  the  edge  of  the  cover  M.  The 
cover  is  insulated  from  the  vessel  containing  the  electrolyte 
by  the  ebonite  blocks  B'.  The  clamping  screw  D  conducts 
the  current.  In  the  chamber  formed  by  the  transverse  parti- 
tions a'  is  the  anode  E,  likewise  provided  with  ribs  e ;  e1  is 
the  conductor  which  is  led  through  the  cover  and  insulated 
therefrom.  The  anode  is  arranged  in  a  bell,£2,  and  projects  into 
the  cylindrical  holder  mz.  The  latter  is  in  one  piece  with  the 
cover  and  closed  in,  gas-tight,  with  paraffin.  The  several  pos- 
itive electrodes  are  naturally  connected  in  parallel.  The  an- 

i  Zeitschrift  f.  Elektroch.,  1899-1900,  511. 


PROCESS   OF    HAZARD-FLAMAND. 


59" 


odes  are  surrounded  by  diaphragms,  which  consist  of  long  gut- 
ters, H,  of  Y-shaped  section  made  of  ebonite,  porcelain,  glass, 
etc.  The  upper  parts  of  these  run  underneath,  almost 
touching  the  bottom  of  the  next  gutter  below.  The  rings- 


Fig.  34- 

have  attachments,  h  (Fig.  34),  in  order  to  hold  them  tightly 
in  place.  The  lower  ring  rests  with  its  side  projections  upon 
the  insulated  cap  /,  which  latter  has  the  function  of  prevent- 
ing hydrogen  evolved  from  the  bottom  of  the  vessel  from  pass- 
ing into  the  anode  chambers.  The  uppermost  ring  //is  of  a 
different  shape  from  the  others  for  the  purpose  of  closing  per- 
fectly the  anode  cells.  The  cover  M  projects  downwards  into 
the  uppermost  gutter  h'  by  means  of  the  circular  flange  m~ 


6o 


ELECTROLYSIS   OF   WATER. 


Fig  35 

The  gases  are  collected  in  two  canals.  A",  in  the  cover,  con- 
nected by  suitable  openings,  ;/,  in  the  respective  cells.  The 
pipe  connections  branch  from  these  canals.  The  flanges  m1 
in  the  cover  are  the  containers  which  communicate  with  the 
inside  of  the  decomposition  vessel  and  are  rilled  with  elec- 
trolyte. This  prevents  escape  of  gas  from  the  openings  h*  and 
m3.  While  the  apparatus  is  in  action,  if  the  level  of  the  fluid 
in  m1  varies  through  inattention,  the  gas  will  escape  into 
the  air  through  ;«3,  but  without  mixing  in  the  apparatus.  Like- 
wise, no  mixing  of  gas  takes  place  if  the  internal  pressure 
rises  because  of  irregularities  in  the  conducting  off  of  the  gas,, 
as  in  that  case  the  gas  escapes  from  the  apparatus  as  soon  as  the 
level  of  the  liquid  has  sunk  to  the  lower  edge  of  the  bell  m. 


PROCESS  OF  GARUTI.  6 1 

PRACTICE. 

Nothing  is  known  of  any  industrial  application  of  this  some- 
what complicated  apparatus. 

Process  of  Verney,  1899. 

A  similar  idea  is  embodied  in  P.  J.  F.  Verney's  invention, 
French  patent  280,374*. 

This  apparatus  is  intended  primarily  for  the  electrolytic  de- 
composition of  water,  but  is  also  suitable  for  the  decomposi- 
tion of  other  electrolytes,  for  the  purpose  of  obtaining  gas. 

FORM  OF  APPARATUS. 

The  apparatus  consists  of  a  metallic  box,  divided  above  into 
a  number  of  chambers  by  a  series  of  partitions  cast  in  one 
piece  with  the  external  shell.  The  external  vessel  with  its 
partitions  serves  for  one  pole  and  the  other  pole  is  formed  of 
metallic  sheets  contained  in  the  compartments  of  the  box.  In- 
sulating rings  of  Y-shaped  section  are  arranged  around  these 
grooved  sheet  electrodes,  the  downward-plunging  part  of  each 
ring  extending  into  the  cover-shaped  enlargement  of  the  ring 
beneath,  without,  however,  touching  it.  By  this  means  suf- 
ficient permeability  section  for  the  current  is  provided,  with 
at  the  same  time  complete  separation  of  the  gases. 

This  is  therefore  a  patenting  of  the  same  subject  under  two 
different  names. 

PRACTICE. 

Verney's  apparatus  had  no  application  in  practice  at  least 
as  far  as  the  author  can  learn. 

Both  of  the  latter  described  apparatus  remind  one  in  many 
ways  of  the  curtain  diaphragms  such  as  have  been  proposed 
for  the  technical  electrolysis  of  the  alkaline  chlorides. 

<c)    With  Complete  or  Perforated  Conducting  Partitions. 
Process  of  Garuti,  1893. 

P.  Garuti  introduced  a  new  principle  as  far  as  concerns  the 

1  L'lnd.  £lectro-chim.,  Ill  (1899),  31. 


62  ELECTROLYSIS  OF  WATER. 

practical  operation  of  electrolytic  apparatus  for  decomposing 
water.  In  the  first  claim  of  his  German  patent  of  July  25, 
1892,  he  specifies  the  following  improvements: 

PATENT  CLAIM. 

"An  electrolytic  apparatus  characterized  by  the  use  of 
partial  metallic  partitions  between  the  cells  containing  the 
two  electrodes,  whereby  the  tension  used  is  so  reduced  that 
no  permanent  decomposition  takes  place  at  the  partition  but 
the  principal  current  passes  through  the  opening  in  the  par- 
tition, for  the  purpose  of  obtaining  cells  of  greater  strength 
and  resistance  against  the  influence  of  the  electrolyte  than  is 
obtained  by  the  use  of  the  old  materials,  and  yet  to  com- 
pletely prevent  the  danger  of  a  reunion  of  the  final  products 
(formation  of  detonating  gas). 

Several  good  descriptions  of  the  principle  of  this  new  idea 
of  Garuti's  have  appeared  in  the  Italian  technical  journals.1 
Garuti  claimed  that  the  diaphragms  used  previously  to  his 
invention  have  too  high  resistance,  are  used  up  too  quickly, 
and  therefore  require  too  many  renewals.  He  claims  that 
even  the  best  diaphragms  still  possess  the  possibility  of  allow- 
ing a  partial  admixture  of  gas  to  take  place,  as  well  as  the 
formation  of  precipitates  in  the  pores  of  the  diaphragm  which 
increase  the  resistance  of  the  same. 

PRINCIPLE. 

It  is  a  fact  that  before  Garuti  no  one  had  thought  of  using 
complete  metallic  plates  in  the  electrolysis  of  water,  since  the 
latter  should,  according  to  the  theory  of  intermediate  elec- 
trodes (bipolar),  evolve  on  the  side  towards  the  anode  some 
hydrogen,  and  on  the  side  towards  the  cathode  some 
oxygen,  a  principle  which  is  made  use  of  practically  in  many 
forms  of  apparatus. 

If  we  bring  into  a  vessel  filled  with  acidulated  water  (Fig, 
36),  two  electrodes,  and  separate  the  same  by  a  metallic  par- 

1  L'Elettricita,  1899,  37,  502  ;  L'Ind.  £lecto-chim.,  Ill,  113. 


PROCESS   OF    GARUTI. 


tition  ^,  (Fig.  37),  there  is  formed  two  separate  decomposing 
cells  and  the  partition  acts  as  a  bipolar  electrode  evolving 
hydrogen  in  the  anode  compartment  and  oxygen  in  the  cathode 
compartment. 

Since,  as  has  frequently  been  mentioned,  the  electrolytic 
decomposition  of  water  requires  approximately  1.5  volts,  with 
the  introduction  of  the  plate  we  require  at  least  3  volts  ten- 
sion to  produce  it  since  evolution  of  gas  takes  place  at  both 
surfaces  of  the  secondary  electrode.  If  the  partition  is,  how- 
ever, raised  so  that  the  fluids  in  J/and  A7"  can  communicate 
by  a  passage  as  is  shown  in  Fig.  38,  and  the  voltage  used  be- 

&  -T>    +  a  -L    ±* 


M 


N 


Fig.  36.  Fig.  37.  Fig.  38. 

tween  a  and  b  is  correspondingly  reduced,  this  evolution  of 
gas  occurs  only  at  the  end  electrodes  and  not  upon  the  metallic 
partition.  The  partition  will,  therefore,  act  only  as  a  bi- 
polar electrode,  when  we  employ  more  than  3  volts  tension 
between  the  poles  a  and  b.  The  metallic  partition,  therefore, 
takes  no  part  in  the  electrolysis  as  long  as  the  tension  used 
is  not  very  much  greater  than  that  needed  for  a  single  decom- 
position cell. 

According  to  a  recent  communication  of  Buffa1,  the  priority 
of  this  observation  is  due  to  the  Italian  Del  Proposto,  while 
Garuti,  in  company  with  Pompili,  applied  the  idea  technically 
for  the  construction  of  various  forms  of  apparatus  for  the  elec- 
trolytic decomposition  of  water. 

According  to  the  patent  application  of  Garuti,  previously 
alluded  to,  the  fundamental  form  of  the  apparatus  may  be  de- 
scribed in  the  following  words  : 

1  Bulletin  de  1'Associat.  des  Ing.  Electr.,  11,  305  (1900). 


64 


ELECTROLYSIS  OF   WATER. 


FORM  OF  APPARATUS. 

u  A  practical  form  of  apparatus  characterized  by  a  holder  or 
container  in  the  form  of  a  gasometer  bell  dipping  into  the 
electrolyte  and  provided  with  two  collecting  chambers  sur- 
rounding the  electrodes,  and  to  the  walls  of  which  are  soldered 
metallic  diaphragms  parallel  to  each  other  and  hermetically 
tight,  for  the  purpose  of  accelerating  the  separation  of  the 


Figs.  39  and  40. 

evolved  gases  from  the  electrodes,  to  give  to  the  gas  the*nec- 
essary  pressure  for  their  use  and  to  make  irregularities  in  their 
production  at  once  perceptible." 

Garuti  used,  in  his  first  apparatus,  electrodes,  supports  and 
even  vessels  of  lead. 

The  drawings  of  the  first  Garuti   apparatus  referred,  as  far 


PROCESS   OF   GARUTI.  65 

as  can  be  learned  from  the  patent  description,  to  a  model  left 
with  the  German  office,  suitable  for  a  current  of  17  amperes. 

The  apparatus  as  shown  in  Figs.  39-44  consists  of  a  wooden 
box  A  lined  with  sheet  lead  a.     This  box  holds  the  electrolyte 


Fig.  41. 


Fig.  42 


Fig.  43- 


as  well  as  the  electrolyzing  apparatus  itself,  and  stands  upon 
insulators  M.  Twelve  per  cent,  sulphuric  acid  is  used  as  elec- 
trolyte with  lead  electrodes. 

The  real  electrolyzing  apparatus  consists  of  a  rectangular 
box  open  beneath,  Fig.  43,  divided  by  metallic  plates  into 
long,  narrow  divisions  n.  These  plates  form  the  metallic  walls 
for  the  separation  of  the  gases.  The  electrodes  are  introduced 
into  the  chamber  thus  formed  by  means  of  the  wooden  comb 
Fig.  44,  which  serves  at  the  same  time  for  insulating  the 


66 


ELECTROLYSIS    OF    WATER. 


electrodes  from  each  other  and  the  metallic  partitions.  Fig. 
40  shows  best  in  its  horizontal  section  the  arrangement  of  the 
electrodes,  their  connection  with  the  main  electrical  conduc- 
tors, as  well  as  the  position  of  the  partition  walls,  n  being  the 
metallic  diaphragms,  cC  the  one  pole,  b  the  end  of  the  other 
pole. 

The  distance  of  the  electrodes  apart  is  10-20  mm.,  the 
height  of  the  electrodes  140  mm.;  the  anodes  are  somewhat 
heavier  than  the  cathodes  to  allow  for  the  production  of  super- 
oxide,  the  former  being  about  3  mm.  in  thickness,  and  the 
latter  i  mm. 

The  electrodes  are  prevented  from  coming  in  contact  with 
the  bottom  of  the  inverted  diaphragm  chest  by  means  of  fork- 
shaped  pieces  of  wood  resting 
upon  (Fig.  44)  similar  perfo- 
rated pieces  of  wood.  Naturally 
the  electrodes  stand  free  from 
the  end  surfaces  of  the  box. 
Likewise  also,  the  connecting 
pieces  O  (Fig.  42),  which  con- 
nect in  parallel  the  electrodes 
of  like  polarity,  must  be  insula- 
ted from  the  back  walls  of  the 
diaphragm  chest.  When  the  in- 
sulating parts  are  removed,  both 
systems  of  electrodes  may  be  easily  lifted  sideways  out  of  the 
diaphragm  chest.  The  conductors  are  fastened  to  the  screw- 
clamps  b1  b2  (Fig.  41).  The  spaces  formed  by  the  diaphragms 
are  alternately  perforated  and  their  exits  are  united  with  two 
parallel-arranged  gas  collectors  G  (Figs.  41  and  43).  The 
height  of  these  chambers,  which  serve  likewise  to  regulate 
the  pressure,  must  be  changed  with  the  pressure  desired.  The 
gases  pass  from  these  chambers  by  the  lead  tube  6*.  Above 
these  exit  tubes  are  wider  tubes  ^,  made  of  insulating  material 
(porcelain  or  glass),  and  the  main  gas  conductors  connect 
only  to  these  in  order  to  insulate  the  apparatus  electrically.  A 


Fig.  44- 


PROCESS   OF  GARUTI. 


67 


lead  tube  H,  likewise  soldered  to  the  gas  chamber  allows[a  gas- 
tight  joint  to  be  made  by  filling  with  water  between  H  andlS. 
The  whole  system  of  electrodes  and  partitions  rests  upon 
two  wooden  stringers  6  cm.  high  in  order  to  avoid  any  short 
circuits  in  consequence  of  the  falling  down  of  peroxide  and 
stopping  up  of  the  apparatus  by  precipitation  from  the  elec- 
trolyte. Two  iron  handles,  L  (Fig.  41),  covered  with  lead, 
permit  the  whole  system  to  be  raised  out  of  the  box.  Two 
amperes  per  sq.  dm.  is  described  as  a  suitable  current  density 
for  dilute  sulphuric  acid  of  the  above  given  concentration. 

VARIATION    OF   APPARATUS. 

Garuti  describes  in  his  German  patent  still  another  modi- 


45 


Fig.  46. 


fied  form  of  his  apparatus  which  makes  a  separation  of  the 
gases  good  enough  for  industrial  purposes.  This  is  shown  in 
Figs.  45  and  46. 

The  most  important  difference  between  this  modification 
and  the  previously  described  apparatus  consists  in  an  enlarge- 


68  ELECTROLYSIS   OF   WATER. 

ment  of  the  distance  between  the  electrodes  to  about  30  mm. 
and  an  alteration  in  the  form  of  the  partitions.  The  latter  are 
not  at  the  same  height  in  the  whole  apparatus,  but  diminish 
towards  the  middle  of  the  apparatus  so  that  the  effective  elec- 
trode surface  is  increased.  This  results  naturally  in  a  greater 
danger  of  the  formation  of  mixed  gas,  which,  however,  is 
taken  care  of  by  the  greater  distance  between  the  electrodes 
and  the  higher  water  pressure.  The  chamber  G  must  there- 
fore be  correspondingly  deeper.  By  this  arrangement  Garuti 
intends  to  use  a  current  density  of  4  amperes  per  sq.  dm.  with 
a  voltage  not  higher  than  in  the  type  of  apparatus  previously 
described. 

The  testing  of  the  Garuti  cell  in  practice,  and  the  experi- 
ence accumulated  therewith,  made  the  introduction  of  various 
improvements  necessary.  According  to  communications  in 
the  technical  journals  of  1899*,  Garuti  has  dropped  the  use  of 
lead  for  the  electrodes  and  partitions.  These  changes  are 
rendered  necessary  by  the  irregular  action  of  the  formation  of 
superoxides  and  particularly  also  by  the  weakness  of  the  lead 
which,  by  getting  out  of  shape,  made  very  disagreeable  short 
circuits  possible  in  such  an  apparatus,  with  very  narrow 
chambers.  Garuti  therefore  passes,  as  other  inventors  before 
him,  to  the  use  of  iron.  This  requires  also  a  change  in  the 
electrolyte,  which  Garuti  likewise  changed  to  caustic  alkali 
solution. 

The  improved  apparatus  (Fig.  47-50),  retains  its  general 
form,  but  the  outer  box  as  well  as  the  electrode  system  is  of 
iron. 

The  distance  of  the  electrodes  from  each  other  is  decreased 
to  12  mm.  in  order  to  increase  the  efficiency  of  the  apparatus 
while  the  distance  of  the  lower  edge  of  the  electrodes  from  the 
bottom  of  the  containing  vessel  is  reduced  to  12  cm.  The 
partitions  are  no  longer  entire  but  have  a  zone  of  fine  perfo- 
rations 4  cm.  wide  placed  by  Garuti  at  first  at  the  lower  edge 

1  L'Elettricita,  1899,  37,  502  ;  L'Ind.  £lectro-chim.  11,  113  (1899). 


PROCESS    OF    GARUTI. 


69 


of  the  electrodes,  according  to  Fig.  48,  and  later  at 
the  level  of  the  middle  of  the  electrodes,  as  shown  in  Fig. 
49.  These  two  alterations  form  the  substance  of  the  German 

h  nA 


OOOOOODOO  O  O  OO  O  G  CO 
O  O  O  O  O  O-5 

o  o  o  o  o  oo 
Fig.  48. 


S 


Fig.  47- 


patents  83,079  and  106,226,  which,  however,  are  not  taken  out 
in  the  name  of  Garuti,  but  by  the  German  license — the  So- 
cie'te  anonyme  1'Oxyhydrique,  of  Brussels.  The  correspond- 


Fig.  49-  Fig.  50. 

ing  English  patents  are  those  of  Garuti  and  Pompili,  num- 
bers 23,663/96  and  12,950/1900. 

In  the  latter  patents  Garuti  also  describes  a  new  form  of 
diaphragm  chamber,  the  length  of  which  in  the  older  type  of 
apparatus  is  often  two  metres,  causing  considerable  difficulty 
in  its  manufacture. 


ELECTROLYSIS   OF   WATER. 


The  new  manner  of  manufacture  and  connecting  up  the 
diaphragm  chamber  consists  in  the  following  : 

A  rectangular  sheet  of  the  length  of  the  electrolyzer  and 
about  twice  as  high  is  cut  through  along  the  middle  line  b  c 
(Fig.  51)  somewhat  over  half  way,  and  thereby  divided  into 
three  parts  efg.  The  two  laps  ^/are  now  bent  over  along 
the  lines/  i  h  at  right  angles,  but  in  opposite  directions.  The 
sheet  represents  thereby  the  shape  shown  in  plan  in  Fig.  52, 
in  section  in  Fig.  54,  in  perspective  in  Fig.  53. 

/ 


c__ 

_\ 

__Z  

c 

/ 

a> 

a 

r 

Fig. 


Fig.  52- 


This  forms  two  cell-like  spaces,  m  and  /z,  each  having  a 
length  of  half  the  sheet  used.  In  building  up  the  diaphragm 
chest  from  such  pieces,  each  edge  k  of  one  piece  is  connected 
with  the  edge  /  of  the  next  box.  The  combination  of  two 
such  elements  x y,  is  shown  in  Figs.  55  and  56.  The  line  2  is 


u 


£ 

1     2 

R        1 

Fig.  53- 


Fig.  54- 


the  point  of  union  of  the  two  cell  elements.  The  diaphragm 
chest  (Fig.  57)  obtained  in  this  way  contains,  therefore,  cells, 
which,  considered  from  the  middle  line  r  j,  are  open  above  on 
one  side  and  closed  above  on  the  other.  Then  all  the  cham- 
bers m  contain,  for  instance,  anodes  and  all  the  chambers  n 
cathodes  ;  thus  the  gas  escapes  separated  at  both  sides  of  the 
apparatus.  By  this  arrangement  of  the  diaphragm  chest, 
Garuti  reaches  a  simplification  of  the  points  of  contact  com- 
pared to  his  older  construction. 


PROCESS   OF   GARUTI. 


All  insulating  parts  are  of  asbestos,  which  is  not  attacked 
by  the  dilute  caustic  soda  solution.  Lead  and  zinc  soldering 
is  to  be  avoided. 

The  partitions  project  below  the  electrodes  at  their  under 


\                       / 

I                   ! 

k                 / 

\                   / 

I            '      !    ' 

i     \          I 

^           / 

\    I      /            I 

\                  V* 

xg 

v-\ 

>A;          I 

i         /      \ 

/ 

"~~~V                \ 

N       ! 

1  / 

/                        \ 

7                         vl 

A                                 \</                                  \ 

Fig.  55-  Fi&-  56. 

edges,  but  sufficient  space  is  left  between  them  and  the  bottom 
of  the  apparatus  for  accumulation  of  impurities  from  the  elec- 
trolyte. The  separation  (yl 
of  the  gas  is  thus  made 
perfect.    Since  the  elec- 
trolyzer   is  closed,  the 
electrolyte   absorbs   no 
carbon  dioxide  from  the 
atmosphere.      The  gas 
chambers  have   under- 
gone no  particular 
changes  except  the  use  \J3 
of   the  water-gauge  in 

connection  with  them.  The  hydraulic  seal  for  the  gas  exit 
tubes  is  retained.  The  apparatus  normally  works  with  200 
to  400  amperes. 

Figs.  58  and  59  show  the  most  recent  practical  apparatus  of 
Garuti's  taken  from  a  treatise  of  Buff  a1,  who  gave  a  lecture  on 
this  subject  before  the  Association  des  Inge*nieurs  Electriciens 
in  Luttich. 

Del  Proposto,  the  clever  originator  of  the  Garuti  idea,  also 
constructed  an  improvement,  the  arrangement  consisting  of 
four  thin  steel  sheets  rolled  up  into  a  spiral  and  separated  from 

1  Bulletin  de  1'Assoc.  des  Ing.  Electr.,  11,  305  (1900).     Nernst-Borchers 
Jahrbuch  der  Elektrochemie,  VII,  338  (1901). 


ELECTROLYSIS   OF   WATER. 


Fig.  58. 


each  other  by  insu- 
lating rods;  two  of 
the  spirals  serve  as 
electrodes  and  two  as 
diaphragms. 

OPERATION. 

Concerning  the  op- 
eration of  the  Garuti 
apparatus,  we  can,  in 
general,  repeat  the  in- 
formation  of  the 
Schmidt  publication 
exactly  as  on  the  for- 
mer pages.  We  can 
add  to  this  the  infor- 
mation given  by 
Buffa  as  follows  :  . 

The  gases  are  led 
to  the  gasometers 
through  iron  tubes 
cont ai ning  insula- 
ting sections  of  rub- 
ber. The  enlarge- 
ment in  the  vertical 
tube  coming  from 
the  apparatus  shown 
in  Fig.  58  keeps  back 
foam  and  spray  of 
the  electrolyte.  The 
same  drawing  also 
shows  the  hydraulic 
seal  which  prevents 
the  mixture  of  the 
gases  in  the  electro- 
lyzer  by  stopping  any 


PROCESS    OF   GARUTI. 


73 


increase  of  gas  pressure  in  the  apparatus.  After  the  gases  have 
remained  some  time  in  the  gasometers,  in  order  to  condense  the 
water  vapor,  they  pass  to  the  compressors.  Garuti  lubricates 
the  compression  cylinder  used  for  oxygen  with  water,  since 
the  compressed  oxygen  will  ignite  the  lubricating  oil  with  an 
explosion. 

Also  in  the  Garuti  apparatus  are  to  be  found  safety  appli- 
ances in  order  to  indicate  at  once  any  mixture  of  gases  in  the 
electrolyzer.  As  in  the  Schmidt  apparatus  two  feeble  currents 
of  gas  are  led  off  and  conducted  over  a  piece  of  platinum 


sponge.  As  long  as  the  gases  were  pure  they  burned  with  a 
quiet  flame.  The  occurrence  of  small  explosions  and  the  ex- 
tinguishing of  the  safety  flame  shows  admixture  of  the  gases. 
Naturally  water  flasks  and  safety  wire  meshes  are  used  to  pre- 
vent the  explosions  from  striking  back  into  the  interior  of  the 
electrolyzer. 

The  usual  accessories  of  a  Garuti  plant  consist  of  the  usual 
manometer  tubes,  a  control  voltmeter  for  the  baths  and  the 
distribution  pipes  for  the  water. 

PURITY  OF  THE  GASES. 

According  to  Buffa,  the  Garuti  apparatus  furnishes  hydro- 


74  ELECTROLYSIS    OF    WATER. 

gen  98.9  per  cent,  pure  by  chemical  analysis,  to  98.5  per  cent, 
pure,  according  to  their  specific  gravity.  The  oxygen  is  97 
per  cent.  If  purer  gases  are  desired  they  can  naturally  be 
prepared  in  the  same  way  as  was  described  in  the  Schmidt 
apparatus,  /'.  £.,  by  passing  them  through  red-hot  tubes  or 
other  substances  which  cause  combination  by  catalysis. 

In  the  Garuti  apparatus  the  purity  of  the  hydrogen  is 
usually  not  determined  by  chemical  analysis  but  by  the  den- 
simeter constructed  by  Bassani. 

This  instrument,  according  to  Buffa,1  is  based  on  the  law 
of  Graham,  according  to  which  the  exit  velocity  of  a  gas 
through  an  opening  is  inversely  proportional  to  the  square 
root  of  its  density. 

In  the  Bassani  densimeter  a  determined  quantity  of  gas  is 
collected  in  a  movable  bell  and  allowed  to  escape  through  a 
small  hole.  As  the  gas  escapes,  the  level  of  mercury  which 
surrounds  the  bell  and  into  which  the  latter  dips,  changes. 
The  beginning  and  the  end  of  the  escape  of  gas  is  determined 
electrically  by  a  second  counter  which  gives  exactly  the  du- 
ration of  the  outflow.  The  influence  of  temperature  and  at- 
mospheric pressure  are  allowed  for  by  suitable  arrangements. 

COST  OF  OPERATION. 

Winssinger2  gave,  in  1898,  some  data  on  the  cost  of  opera- 
ting the  Garuti  apparatus.  According  to  this  a  plant  in  opera- 
tion in  Brussels,  produced  0.4  litre  of  hydrogen  and  0.2 
litre  of  oxygen  per  ampere  hour.  A  normal  apparatus  of 
350  amperes  and  2.5  volts  produced  per  twenty-four  hours 
1.68  cubic  metres  of  oxygen  and  3.36  cubic  metres  of  hydro- 
gen. The  quantity  of  energy  required  daily  is,  therefore, 
21,000  watt-hours,  wherewith  altogether  5.04  cubic  metres  of 
the  two  gases  were  obtained.  The  average  consumption  of 
energy  is,  therefore,  4,166  watt-hours  per  cubic  metre  of  the 

1  Bull,    de  1'Assoc.    des   Ing.    Electr.,  1900,    11,  305  ;  Nernst-Borchers : 
Jahrbuch  der  Electrochemie,  VII,  341. 

2  Chem.  Ztg.,  22,  609  (1898). 


PROCESS  OF  GARUTI.  75 

two  gases.  Buffa  in  the  lecture  previously  alluded  to  re- 
peated these  figures  as  representing  present  practice.  The 
current  output  is,  therefore,  in  this  apparatus  about  96  per 
cent.,  and  the  energy  output  57  per  cent. 

If  we  calculate  the  energy  used  upon  only  one  of  the 
two  gases,  for  in  making  gas  the  obtaining  of  only  one  of 
the  gases  is  sometimes  the  purpose  of  the  operation,  we  will 
find  an  energy  requirement  of  12,500  watt-hours  per  cubic 
metre  of  oxygen  and  6,250  watt-hours  per  cubic  metre  of  hy- 
drogen. 

The  required  voltage  varies  according  to  the  concentration 
of  the  electrolyte  and  is,  according  to  Buffa,  for 

Water  acidulated  with  sulphuric  acid 3.00  volts 

Caustic  soda  solution  21°  Beaume" 2.45     " 

Caustic  potash  solution  16°  Beaume' 2.55     " 

Caustic  potash  solution  18.5°  Beauine" 2.45     ' ' 

With  power  costing  j£-i#  cents  per  kilowatt-hour  the 
cost  of  power  figures  out  to  be  for 

i  cubic  metre  of  oxygen 3.1250-15.6250  cents 

i  cubic  metre  of  hydrogen 1.5625-  7.8125      " 

i  cubic  metre  of  detonating  gas 1.0400-  5.2075      " 

Sinking  fund  and  interest  on  the  plant,  patent  royalties? 
labor  and  consumption  of  electrodes  are  naturally  not  in- 
cluded in  the  above  figures. 

In  a  plant  set  up  in  Rome,  the  power  cost  $19.82  per  kilo- 
watt-year. This  corresponds  approximately  to  J^  cent  per 
kilowatt-hour.  At  this  price  of  power  the  total  operating 
cost  for  i  y^,  cubic  metres  of  mixed  gas  is  calculated  by  Buffa 
at  4  cents,  not  including  sinking  fund  and  interest.  This 
amounts  to,  then,  according  to  which  gas  is  used,  a  cost  for 

i  cubic  metre  of  oxygen 8  cents 

i  cubic  metre  of  hydrogen 4     " 

i  cubic  metre  of  detonating  gas 2.65  cents 

Interest  and  sinking  fund  will  raise  these  figures  to  the 
following : 

i  cubic  metre  of  oxygen 15  cents 

I  cubic  metre  of  hydrogen 7.5    " 

i  cubic  metre  of  detonating  gas 5       " 


76  ELECTROLYSIS   OF   WATER. 

The  compression  of  the  gases  would  increase  the  cost  of 
operation  to  the  following: 

i  cubic  metre  of  oxygen 17  cents 

i  cubic  metre  of  hydrogen 8.5    " 

i  cubic  metre  of  detonating  gas 5.65  cents 

This  small  increase  of  operating  expenses,  ascribable  to 
compressing  the  gas,  is  so  low  that  it  cannot  include  sinking 
fund  and  interest  on  the  supply  of  flasks  necessary  for  contain- 
ing the  gas. 

COST  OF  PLANT. 

The  cost  of  a  100  H.  P.  plant,  including  buildings,  motor 
and  dynamos,  51  cells,  using  each  400  amperes,  2  gasometers 
holding  each  100  and  50  cubic  metres  respectively,  is  given 
by  Buffa  at  $14,000,  which  figures  are  increased  to  $20,000, 
if  it  is  necessary  to  transform  the  current  and  compress  the 
gas.  The  first  cost  of  the  necessary  flasks,  however,  is  notin. 
eluded  in  the  above  estimate. 

PRACTICE. 

Plants  using  the  Garuti  system  are  in  operation  for  various 
purposes  in  Rome,  Tivoli,  Terni,  by  the  Societe  1'Oxyhydrique 
in  Brussels,  and  the  Sauerstoff-  und  Wasserstoffwerken  in  Lu- 
zern.  Besides  these  the  Societe  de  Montbard,  writh  the  pre- 
viously mentioned  Brussels  company,  are  erecting  a  plant  in 
Montbard  which  will  use  over  60  H.  P.,  and  will  produce, 
working  twenty  hours  daily,  180  cubic  metres  of  hydrogen  and 
90  cubic  metres  of  oxygen.  This  combined  company,  with  a 
capital  of  1,000,000  francs,  is  named  L/Oxhydrique  francaise. 

Fig.  60  shows  a  view  of  the  Garuti  water-decomposing  plant, 
in  Brussels,  the  picture  being  taken  from  the  last  publication 
of  Schoop1. 

Schoop  gives  the  following  data  about  the  plant  of  the 
Sauerstoff-  und  Wasserstoffwerken  in  L,uzern2. 

The  three-phase  alternating  current  is  taken  from  the  elec- 

1  M.  U.  Schoop  :  Die  industrielle  Elektrolyse  des  Wassers,  1901,  119. 

2  Idem,  p.  122. 


PROCESS   OF   GARUTI. 


77 


trical  company  at  Rathhausen,  at  1500  volts  and  transformed 
in  a  rotary  converter  to  a  direct  current  of  75  volts.     There 


Fig.  61. 


are  16  large  and  32  small  electrolyzers,  which,  in  twenty-four 
hours,  produce  approximately  50  cubic  metres  of  oxygen  and 


78  ELECTROLYSIS   OF   WATER. 

ioo  cubic  metres  of  hydrogen.  The  corresponding  gasometers 
contain  60  and  120  cubic  metres  respectively.  The  two  com- 
pressors can  compress  44  cubic  metres  of  gas  per  hour. 

The  oxygen  compressor  was  furnished  by  Thirion,  of  Paris, 
and  can  compress  8  cubic  metres  of  oxygen  per  hour  to  150 
atmospheres,  with  a  power  consumption  of  2.5  H.  P.  The 
hydrogen  compressor,  made  by  Schutz  in  Wurzen,  requires  7 
H.  P.  for  an  output  of  36  cubic  metres  of  hydrogen  per  hour, 
compressed  to  200  atmospheres. 

Fig.  6 1  shows  a  view  of  the  electrolyzers  used  in  Luzern. 

A  more  detailed  description  of  the  plant  in  Rome  is  given 
by  Buff  a  in  the  lecture  already  referred  to1  and  the  following 
is  an  exact  reproduction  from  Borchers2.  The  plant  is  oper- 
ated by  Lieutenant  Bossi  and  Captain  Bassani.  A  diagram- 
matic sketch  is  shown  in  Fig.  62. 

In  this  figure  the  parts  are  as  follows  :  A  main  conductors 
(2000  volts),  B  automatic  circuit  breaker,  C  transformer,  D 
safety  fuse,  B  cut  out,  J  automatic  circuit  breaker,  L,  signal 
lamp,  M  asynchronous  single-phase  motor,  P  battery  switch, 
R  resistance,  S  rheostat,  V  voltmeter,  a  ammeter,  p  pole  of 
the  alternating  current  conductor,  q  pole  of  the  direct  cur- 
rent conductor,  r  direct  current  switch,  v  electrolyzing  vessels. 

The  plant  serves  for  the  manufacture  of  hydrogen  for  the 
airship  division  of  the  Italian  army,  and  has  taken  the  place 
of  the  chemical  hydrogen  factory  in  which  the  gas  was  for- 
merly made  by  the  solution  of  iron  in  sulphuric  acid.  The 
gas  obtained  by  the  older  method  weighed  160  grammes  per 
cubic  metre,  while  pure  hydrogen  weighs  89  grammes  per 
cubic  metre. 

The  energy  is  furnished  in  the  form  of  a  2OOO-volt  (52- 
phase)  alternating  current  by  the  electrical  plant  at  Porta  Pia, 
which  itself  receives  this  power  from  the  Tivoli  Falls,  27  kil- 
ometers (16  miles)  distant.  The  primary  current  is  then  con- 

1  Bull,  de  I'Assoc.  des  Ing.  Electr.,  11,  305  (1900). 

*  Nernst-Borchers:  Jahrbuch  der  Elektrochemie,  VII,  336  (1901). 


PROCESS  OF  GARUTI. 


79 


verted  by  means  of  three  transformers,  each  of  30  kilowatt 
capacity.  The  secondary  coils  of  the  transformers  run 
into  a  single  conductor  on  one  side,  on  the  other  side  through 
three  conductors  in  which  automatic  circuit  breakers  are  in- 


80  ELECTROLYSIS   OF   WATER. 

serted.  The  current  is  then  taken  from  the  switchboard  to 
three  single-phase,  asynchronous  motors,  which  are  directly 
coupled  to  three  4-pole,  direct-current  dynamos  (Thury  sys- 
tem), each  of  50  volts  and  of  400  amperes  capacity.  The  com- 
mon conductor  leads  from  the  negative  poles  of  the  dynamos 
to  the  electrolyzing  cells,  while  the  positive  conductors  of  each 
dynamo  pass  to  the  switchboard  upon  which  are  measuring 
instruments,  signal  lamps,  safety  fuses,  circuit  breakers  and 
switches.  The  latter  are  so  arranged  that  each  of  the  three 
dynamos  can  be  connected  with  each  of  the  three  batteries  of 
electrolyzers.  There  are  51  electrolyzing  vessels  divided  into 
three  groups.  Bach  group  of  1 7  cells  is  calculated  for  a  cur- 
rent of  400-450  amperes,  and  require  45  to  50  volts.  The 
electrolyzing  vessels  themselves  are  furnished  by  Garuti  and 
Pompili  of  Rome.  The  arrangement  of  the  apparatus  is  of 
the  type  shown  in  Figs.  58  and  59. 

Process  of  Siemens  Bros,  and  Obach,  1893. 

In  the  group  of  apparatus  with  diaphragms  of  conducting 
material  comes  also  the  construction  of  Siemens  Bros.  &  Co., 
and  Obach,  English  patent  11,973/93  of  the  2ist  of  April, 
1894. 

FORM  OF  APPARATUS. 

The  apparatus  shown  in  Fig  63  consists  of  a  cast-iron  ves- 
sel, #,  surrounded  with  heat-retaining  material.  A  porcelain 
support  carries  as  anode,  the  iron  cylinder,  f,  which  is  con- 
nected with  the  positive  conductor  through  the  iron  rods  ee. 
The  cathode  is  formed  of  a  second  cylinder,  g,  which  is  con. 
nected  with  the  negative  pole  by  the  connections  it.  The 
electrodes  are  insulated  by  raising  them  upon  the  feet  r  r. 
The  diaphragm  is  a  metallic  wire  netting  which  is  fastened  to 
the  hood  c  and  separates  the  gases.  The  porcelain  block  k 
holds  the  wire  netting  fast  in  place.  The  electrolyte  is  dilute 
caustic  soda  solution.  The  gases  escape  by  the  tubes  m'  and 
n1 ',  while  the  water  used  up  is  replaced  through  O.  p  is  the 
water-guage.  The  level  of  the  water  must  necessarily  not 


PROCESS   OF   SIEMENS    BROS.    AND   OBACH. 


81 


sink  below  the  lower 
edge  of  the  hood.  The 
cock  q  serves  for  emp- 
tying the  apparatus  en- 
tirely when  it  needs  to 
be  cleaned.  The  whole 
apparatus  is  set  upon 
insulated  porcelain  feet. 
The  apparatus  is  rec- 
ommended by  its  man- 
ufacturers as  being  of 
great  durability,  and 
very  small  resistance. 
The  slight  possibility 
of  a  mixture  of  the 
gases  must  not  be  for- 
gotten, and  in  fact  the 
degree  of  purity  of  the 
gas  is  given  as  95  per 
cent.,  while  other  appa- 
ratus already  described 
obtain  a  somewhat 
higher  content. 

In  certain  respects  the  apparatus  may  be  taken  for  a  modi, 
fication  which  Garuti  applied  to  his  apparatus,  for  the  use  of 
the  finely  perforated  strips  in  the  sheet  diaphragms  by  Garuti 
plainly  underlies  the  idea  on  which  the  apparatus  of  Siemens 
Bros.  &  Obach  is  based. 

The  exterior  of  a  commercial  Siemens  Bros.  &  Obach  ap- 
paratus is  shown  in  Figs.  64  and  65. 

The  normal  type  of  this  apparatus  is  built  for  a  current  of 
750  amperes  at  3  volts. 

OUTPUT. 

Three  such  apparatus  will  furnish  n  cubic  metres  of  oxy- 
gen and  22  cubic  metres  of  hydrogen  in  twenty-four  hours, 
requiring  162  kilowatt-hours. 


Fig.  63. 


82 


ELECTROLYSIS   OF   WATER. 
Fig.  64. 


Fig.  65. 
COST  OF  OPERATION  AND  PLANT. 

The  cost  of  power  would  therefore  be,  at  the  rates  of  ]^  and 
cents  per  kilowatt-hour, 

#  cent.  i#  cents. 

i  cubic  metre  of  detonating  gas 1.225  6.125 

i  cubic  metre  of  oxygen 3.675  18.375 

i  cubic  metre  of  hydrogen 1.850  9.250 


PROCESS   OF  SCHUCKERT.  83 

The  cost  of  such  a  plant  with  three  electrolyzers  is  esti- 
mated as  follows : 

Three  electrolyzers  for  750  amperes  each  at  3  volts, 
including  two  connecting  cables,  one  funnel,  two 
run-off  cocks,  and  two  test  cocks $  562.50 

One  dynamo  750  amperes,  9  volts,  including  a  sliding 
base 650.00 

Measuring  instruments,  switches,  safety  fuses,  etc....        75.00 

Total $1287.50 

Not  including  motor,  erection,  electrical  conductors,  foun- 
dation work,  as  well  as  the  piping  for  the  carrying  off  of  the 
gases  from  the  electrolyzers. 

Process  of  Schuckert,  1896. 

As  we  have  said  on  page  44,  the  apparatus  of  The  Elek- 
trizitats-Akt.-Ges.,  formerly  Schuckert  &  Co.,  belongs  really 
to  the  arrangements  with  insulating  partitions.  We  will  de- 
scribe it,  however,  in  spite  of  this,  in  this  class  since  it  re- 
minds one  in  several  constructive  details  of  the  Garuti  ar- 
rangement. 

We  cannot  give  a  complete  description  of  the  Schuckert  ap- 
paratus since  it  has  not  been  patented,  and  the  author  must 
limit  himself  to  the  ideas  which  the  firm  in  question  have 
placed  at  his  disposal  without  injuring  their  business  interests. 
On  the  other  hand  the  German  provisional  patent  80,504,  of 
September  i8th,  1896,  gives  some  fundamental  data. 

According  to  this  patent,  The  Elektrizitats-Akt.-Ges.,  for- 
merly Schuckert  &  Co.,  describe  their  patent  as  an  "apparatus 
for  the  electrolytic  manufacture  of  hydrogen  and  oxygen  for 
industrial  purposes,  in  which  an  insulating  partition  is  inter- 
posed between  each  pair  of  unlike  electrodes,  and  an  insula- 
ting bell  is  placed  over  each  electrode." 

PATENT  CLAIM. 

The  patent  claim  reads  : 

"An  apparatus  for  the  manufacture  of  oxygen  and  hydro- 
gen by  the  electrolytic  decomposition  of  caustic  alkali  solu- 
tion, acids,  or  other  suitable  substances,  without  diaphragms, 


84  ELECTROLYSIS   OF   WATER. 

characterized  thereby  that  the  separate  collection  of  the  gases 
is  obtained  by  : 

1.  Using  between  each  pair  of  unlike  electrodes  an  insula- 
ting partition  composed    of   insulating   material  introduced 
through  an  opening  in  the  side  walls,  therefore  easily  replace- 
able, and  which  does  not  dip  so  deeply  into   the  fluid  as  the 
electrodes. 

2.  Bells  of  conducting  or  non-conducting  material,  lying 
upon  the  electrodes  or  insulated  from  them  and  dipping  down 
as  far  as  the  middle  of  the  electrodes." 

After  what  has  been  said,  the  schematic  sketch  of  the  appa- 
ratus shown  in  Figs.  66-68  is  easily  understood  without  further 
description. 

DESCRIPTION. 

The  apparatus  consists  of  a  cast-iron  vessel1  in  which  the 
corresponding  number  of  bells  are  placed,  which  serve  for 
catching  the  gases  evolved  at  the  electrodes,  and  with  the 
exception  of  the  copper  conductors  and  the  insulation,  only 
iron  is  used  in  the  construction  of  the  apparatus. 

The  electrolyte  is  a  15  per  cent,  solution  of  sodium  hydrox- 
ide in  water.  The  water  decomposed  during  the  operation  of 
the  apparatus  must  be  replaced  by  filling  with  distilled  water 
as  is  practiced  in  accumulator  batteries,  in  order  that  the  solu- 
tion retain  its  original  concentration  ;  the  addition  of  sodium 
hydroxide  is  usually  not  necessary. 

The  apparatus  can  be  connected  up  in  series,  each  requiring 
2.8  to  3  volts.  The  electrolyzers  work  best  with  an  electromo- 
tive force  of  about  2.8  volts,  if  the  electrolyte  is  kept  at  a  tem- 
perature of  about  70° C.,  which  results  without  further  provision 
simply  through  the  heat  developed  by  the  current,  if  the  elec- 
trolyzers are  protected  as  far  as  possible  from  radiating  their 
heat.  To  retain  the  heat  in  the  apparatus  they  are  surrounded 
by  the  non-conducting  material  which  is  the  most  easily  ob- 
tained, as  by  placing  them  inside  a  wooden  box  slightly  larger 
than  the  vessel,  and  filling  the  space  in  between  with  sand,  so 

1  Private  communication  from  the  author. 


PROCESS   OF   SCHDCKERT. 


Fig  66. 


Fig.  67. 


Fig.  68. 


that  the  iron  vessel  is  surrounded  on  the  sides  by  a  5  cm. 
layer  of  sand.  This  arrangement  renders  the  apparatus  some- 
what difficult  of  access. 

MANAGEMENT. 

At  the  start  of  the  operation,  the  power  required  by  the 
electrolyzer  is  more  than  the  normal  limit,  since  a  certain 
amount  of  energy  is  necessary  for  heating  the  apparatus,  that 
is  for  bringing  the  apparatus  to  the  temperature  at  which  it 
works  best,  z.  £.,  70 °C. 

When  it  is  possible  to  heat  the  above  by  means  of  steam  to 
the  normal  working  temperature,  this  extra  expenditure  of 
electrical  energy  is  not  required. 

The  gases  evolved  escape  separately  through  iron  nozzles 
to  which  are  attached  rubber  hose  in  order  to  insulate  the 


86  ELECTROLYSIS  OF  WATER. 

electrolyzers  from  the  piping  system.  Then  the  gases  pass 
through  condensing  chambers  and  washing  apparatus  to 
purify  them  from  alkaline  solution  spray,  and  are  then  led  to 
the  gasometers. 

The  gases  can  be  taken  from  the  electrolyzers  at  a  pressure 
up  to  about  60  mm.  of  water;  above  that  pressure,  mixing  of 
the  gases  can  take  place  in  the  apparatus.  By  observing  this 
maximum  pressure,  the  working  of  the  apparatus  is  as  has 
been  shown  in  detail  extremely  safe,  and  the  gases  are  ob- 
tained at  60  mm.  water  pressure  of  the  purity  of  97-98  per 
cent. 

NORMAL  TYPES. 

The  apparatus  are  built  normally  for  a  working  current  of 
600  amperes,  the  cells  being  660  mm.  long,  450  mm.  wide, 
and  360  mm.  high,  outside  dimensions,  and  holding  about  50 
litres  of  solution.  The  weight  of  such  an  apparatus  is  about 
220  kilograms. 

OUTPUT. 

Each  apparatus  produces,  hourly,  220  litres  of  hydrogen 
and  no  litres  of  oxygen  measured  over  water  at  760  mm. 
mercury  pressure  and  at  15°  C. 

The  evolution  of  the  gas  takes  place  continuously.  The 
gases  are  perfectly  safe  from  explosion  on  leaving  the  appa- 
ratus and  their  further  handling  will  cause  no  danger  from 
such  as  long  as  the  piping  system,  and  washing  and  puri- 
fication apparatus,  and  the  compressors  are  installed  in  a  suffi- 
ciently business-like  manner. 

It  is  unnecessary  to  repeat  here  the  cost  of  plant  and  opera- 
ting of  the  Schuckert  apparatus  given  in  the  older  literature1 
since,  in  this  respect,  the  author  is  enabled  to  give  data  from 
the  latest  standpoint,  furnished  by  the  firm  building  the  appa- 
ratus. 

1  Zeitschr.  fiir  Elektrochem.,  1897-1898,  456  ;  Jahrbuch  fur  Elektrochem. , 
1899,  347 ;  Hammerschmidt  and  Hess  :  Chem.  Zeitung,  22,  123  (1898);'  Elek- 
trochem. Zeitschr.,  1898-1899,  191.  L'Ind.  electro- chim.,  II,  30. 


PROCESS   OF  SCHUCKERT.  87 

COST  OF  PLANT. 

The  cost  of  a  plant  for  the  production  of  100  cubic  metres 
of  oxygen  and  200  cubic  metres  of  hydrogen  in  twenty-four 
hours  amounts  to  : 

40  electrolyzers  for  600  amperes  at  $62.50 $2,500.00 

Filling  the  baths  with  electrolyte,  installation  and  foundations  for 

the  electrolyzers,  piping,  ventilation  and  lighting  plant,  erection  1,000.00 
Building,  70  square  metres  of  ground  area 1,000.00 

Total $4,500.00 

This  estimate  of  cost  contains  only  the  purely  electrolytic 
plant ;  the  cost  of  storing  and  compression  of  the  gas  is  not 
included  therein. 

COST  OF  OPERATION. 

The  cost  of  operating,  according  to  the  data  given  to 
the  author,  using  ^  and  i  ^  cents  as  the  limiting  prices  per 
kilowatt  hour,  is  as  follows  : 

68  kilowatt  in  the  electrolyzing  chambers $  4.08  $20.40 

Renewing  of  the  electrodes  and  electrolyte 0.90  0.90 

Repair  and  maintenance  of  the  interior  arrangements  in  the 

cell  room •••• 0.85  0.85 

Repair  of  the  building o.  175  o.  175 

Wages  of  two  workmen 2.125  2.125 

Various  general  expenses 0.75  0.75 

Sinking  fund  and  interest  15  per  cent 2.25  2.25 

Total $11.13        I27«45 

The  cost  amounts,  therefore,  for  a  daily  production  of  300 
cubic  metres  of  mixed  gas  to  the  following  : 

i  cubic  metre  of  mixed  gas 1.36-  6.8  cents. 

i  cubic  metre  of  oxygen 4.08-20.4     " 

i  cubic  metre  of  hydrogen 2.04-10.2     " 

The  cost  of  operation  without  sinking  fund  and  interest  on 
the  gasometers  and  their  appendages  and  without  general  ex- 
penses amounts  to : 

i  cubic  metre  of  detonating  gas 3.71  -9.15    cents. 

i  cubic  metre  of  oxygen 11.13-27.45       " 

i  cubic  metre  of  hydrogen 5.565-13.725     " 

The  cost  of  the  compression  as  figured  by  The  Electrizitats- 


88  ELECTROLYSIS   OF   WATER. 

Akt.-Ges.,  formerly  Schuckert  &  Co.,  is  5-6^  cents  per  cubic 
metre  of  gas,  in  which,  however,  the  interest  and  sinking 
fund  on  the  large  investment  in  steel  flasks  is  not  included. 

PRACTICE. 

According  to  the  information  furnished  the  author,  there  is 
only  one  plant  in  operation  under  the  Schuckert  patents, 
namely,  at  the  platinum  works  of  W.  C.  Heraeus,  in  Hanau. 
The  plant  is  intended  for  a  current  of  200  amperes  at  30  volts, 
and  furnishes  4  cubic  metres  of  oxygen  in  ten  working  hours. 
A  second  plant,  producing  I  cubic  metre  of  oxygen  per  day,  is 
said  to  have  been  erected  in  Berlin,  but  is  no  longer  in  opera- 
tion. 

B.     Processes  and  Apparatus  for  the  Electroly- 
sis of  Water  without  Separation  of  the  Gas 
(Production  of  Detonating  Gas). 

(a)  For  Purposes   of    Instruction  and    Laboratory  Work 

(Voltameter). 

GENERAL. 

In  this  group  belong  a  part  of  the  electrical  measuring  in- 
struments which  depend  on  the  chemical  action  of  the  current. 
The  determination  of  the  strength  of  an  electric  current  can 
be  made  by  measuring  or  weighing  the  amount  of  detonating 
gas  developed  in  an  interval  of  time,  quite  as  well  as  from  the 
weight  of  precipitated  copper  or  silver. 

As  in  the  industrial  decomposing  apparatus,  so  also  in  the 
mixed  gas  voltameter,  either  acid  or  alkaline  solution  may  be 
used.  In  general,  voltameters  with  alkaline  electrolytes  are 
preferred,  since  in  using  sulphuric  acid  inaccurate  values  are 
obtained  by  the  production  of  ozone  and  perstilphuric  acid. 
The  acid  electrolyte  used  is,  as  a  rule,  30  per  cent,  sulphuric 
acid,  corresponding  to  a  specific  gravity  of  1.3  ;  for  more  accu- 
rate determinations,  a  solution  of  phosphoric  acid  is  to  be  pre- 
ferred. The  alkaline  electrolyte  is,  as  a  rule,  a  15  per  cent, 
solution  of  caustic  soda  free  from  chlorine. 

The  mixed  gas  voltameters  are  especially  suited  for  cali- 


PROCESSES   AND   APPARATUS.  89 

brating  instruments,  and  less  suited  as  direct  indicators  of  the 
amperage  of  the  current.  In  this  respect  their  construction 
of  simple  materials  possesses  a  great  ad  vantage.  As  compared 
with  the  silver  and  copper  voltameters  they  have  the  advan- 
tage of  easier  and  simpler  manipulation,  and  the  disadvantage 
of  less  accuracy.  H.  A.  Naber1  has  recently  advised  the  use 
of  the  hydrogen  voltameter. 

REDUCTION  OF  GAS  VOLUMES. 

If  the  measurement  is  made  by  the  determination  of  the 
quantity  of  evolved  mixed  gas,  the  volume  read  off  must  be 
reduced  to  o°  C.  and  760  mm.  barometric  pressure.  For  this 
purpose  the  formula 


1  760(273  H-  1) 

is  used,  in  which  z/x  indicates  the  gas  volume  read  off,  b  the 
barometric  pressure  during  the  experiment,  h  the  tension  of 
water  vapor  at  the  temperature  t  of  the  electrolyte  and  gas. 
In  using  this  formula,  care  must  be  taken  that  when  the  read- 
ing is  taken,  the  level  of  the  fluid  in  the  gas  tube  and  in  the 
principal  water  receiver  stands  at  the  same  height,  which  can 
be  easily  obtained  by  a  careful  raising  of  the  tube  in  the 
vessel. 

In  determining  the  strength  of  the  current,  the  reduced  gas 
volume  must  be  calculated  for  one  minute's  duration  of  ex- 
periment which  is  then  divided  by  10.44,  the  number  of  cubic 
centimetres  of  mixed  gas  evolved  by  i  ampere  in  one  minute. 

When  using  acid  electrolytes  it  is  preferred  to  measure  only 
the  hydrogen  in  order  to  exclude,  as  far  as  possible,  the  influ- 
ence of  secondary  reactions  at  the  anode  ;  then  the  volume  read 
off  and  reduced  by  the  use  of  the  above  formula  must  be  in- 
creased 50  per  cent,  before  dividing  by  10.44. 

At  the  end  of  this  monograph  is  an  appendix  in  which  are 
given  tables  for  the  reduction  of  gas  volumes  to  760  mm. 

1  "Standard  Methods,  etc.,"  by  H.  A.  Naber  and  George  Tacker,  Salis- 
bury, Court  Fleet  Street,  London.  H.  A.  Naber:  "Das  Wasserstoffvoltameter 
und  seine  Zuverlassigkeit,"  Elektrochem.  Zeitscher.  1898-99,  45. 


9O  ELECTROLYSIS   OF   WATER. 

barometric  pressure  and  o°  C.,  and  also  for  the  tension  of 
water  vapor  in  millimeters  of  mercury,  in  the  range  of  ordinary 
temperatures  at  which  experiments  are  made. 

CONNECTIONS  FOR  CALIBRATION  OF  APPARATUS. 

The  connections  used  when  calibrating  with  the  voltameter 
are  shown  in  Fig.  69,  in  which  6*  is  the  source  of  current  con- 
sisting of  batteries  or  accumulators  connected  for  tension. 
The  electromotive  force  of  the  battery  should  be  five  or  six 
times  larger  than  is  necessary  to  decompose  water.  This  has 
the  object  of  diminishing,  as  far  as  possible,  the  fluctuations  in 
the  current  after  closing  the  circuit,  which  may  be  so  large  as 


Fig-  69. 

to  make  readings  of  the  average  value  somewhat  difficult  when 
using  small  tensions.  This  irregularity  at  the  start  lasts  so 
much  the  longer,  the  smaller  the  electromotive  force  of  the 
battery  used  and  the  current  density  at  the  electrodes.  The 
mixed  gas  voltameter  is  therefore  preferable  for  the  measure- 
ment of  small  currents,  while  the  silver  and  copper  voltameter 
is  preferable  for  large  currents.  In  Fig.  69,  V\s  the  voltam- 
eter, G  the  instrument  to  be  calibrated,  R  an  adjustable  resist- 
ance, and  c  a  switch. 

The  accuracy  of  the  measurement  is  dependent  upon  the 
accuracy  of  the  reading  off  of  the  gas  volume  and  is  on  the 
verage  about  0.2-0.3  per  cent. 


PROCESSES   AND   APPARATUS. 


Fig;  7 1. 


SIMPLE  FORMS  OF  APPARATUS. 

Fig.  yo1  shows  a  mixed  gas  voltameter  of  the  simplest  type. 
It  consists  of  a  cylindrical  vessel  filled  with  dilute  acid,  into 
which  dips  a  graduated  tube  closed  above.  The  tube  is  like- 
wise filled  with  the  electrolyte  before  the  experiment.  Inside 
the  tube  at  the  bottom  are  two  platinum  electrodes  connected 
with  the  external  circuit  by  two  insulated  wires. 

VOLTAMETER  OF  KOHLRAUSCH. 

A  simple  form  for  a  current  of  about  30  amperes  was  pro- 
posed by  Kohlrausch.2 

The  apparatus  shown  in  Fig.  71  is  made  by  the  firm  of 
Hartmann  &  Braun,  in  Frankfurt.  It  consists  of  a  glass  tube 
40  mm.  in  diameter,  graduated  in  centimeters  and  with  its  lower 

1  Holzt :  Die  Schule  des  Elektrotechnikers,  I,  102. 

2  Idem,  I,  104. 


ELECTROLYSIS   OF   WATER. 


extension  ground  into  the  neck  of  the  large  vessel.  A  thermom- 
eter isjsealed  into  the  measuring  tube  and  renders  possible  an 
exact  determination  of  the  temperature.  The  platinum  elec- 
trodes are  introduced  through  the  rubber  stoppers,  provided 
by  means  of  the  two  side  connections. 

VOLTAMETER  OF  DE  LA  RIVE. 

A  simple  voltameter  which  has  the  advantage  that  after 
the  evolution  of  gas  it  is  only  necessary  to  invert  the  vessel 
with  the  firmly  attached  glass  tube  in  order  to  refill  it  with 
dilute  acid,  is  shown  in  Fig.  72.  This  apparatus,  designed  by 


Fig.  72.  Fi&-  73- 

De  la  Rive,  allows  in  this  form  the  catching  of  either  one  of 
the  gases.1 

VOLTAMETER  OF  BUNSEN. 

Bunsen2  used  for  exact  measurements  a  voltameter  consist- 

1  Wiedemann  :  Die  Lehre  von  der  Elektrizitat,  II,  477  (iS94)-     Bertin: 
Nouv.  Opusc.  M£m.  de  la  societ£  mat.  de  Strasbourg,  6,  31  (l865)- 

2  Pogg.  Ann.,  1854,  620. 


PROCESSES   AND   APPARATUS.  93 

ing  of  a  glass  flask  (Fig.  73),  in  which  the  platinum  wires 
leading  to  the  electrodes  were  sealed  at  a  a'  and  having  the 
movable  parts  all  ground  in.  The  flask  carries  at  B  a  drying 
tube,  A,  which,  as  well  as  the  enlargement  C,  is  filled  with 
•concentrated  sulphuric  acid,  in  case  the  mixed  gas  is  to  be 
•collected  in  the  dry  condition  over  mercury.  The  tube  carry- 
ing off  the  gas  is  likewise  connected  to  the  drying  tube.  For  de- 
terminations by  weight,  the  little  flask  carries  besides  this  on 
one  side  a  neck  closed  by  a  glass  stopper,  through  which,  after 
the  close  of  the  experiment,  the  mixed  gas  in  the  interior  of 
the  apparatus  may  be  replaced  by  atmospheric  air.  Bunsen 
also  recommends  the  keeping  of  the  apparatus  at  a  tempera- 
ture of  60°  by  means  of  a  water-bath  and  the  use  of  very  dilute 
sulphuric  acid  in  order  to  prevent  the  formation  of  persul- 
phuric  acid,  hydrogen  peroxide,  and  ozone.  Besides  this, 
Bunsen  especially  recommends  the  replacement  of  the  sul- 
phuric acid  by  phosphoric  acid. 

VOLTAMETER  OF  OETTEL. 

Oettel's  voltameter  enjoys  an  extensive  use1.  This,  as  seen 
in  Fig.  74,  consists  of  a  thick-walled,  cylindrical,  glass  vessel 
in  which  is  arranged  two  cylindrical,  concentric,  sheet-nickel 
electrodes,  immersed  in  a  15  per  cent,  caustic  soda  solution 
free  from  chlorine.  The  vessel  is  about  14  cm.  high  and 
about  6  cm.  in  diameter  and  closed  air-tight  by  a  rubber  stop- 
per. To  avoid  short  circuits  between  the  two  concentric  elec- 
trodes, a  straight-walled,  crystallizing  cup  is  placed  in  the  bot- 
tom with  its  walls  between  the  two  electrodes.  This  alkaline 
voltameter  requires  only  a  very  low  tension  to  operate  it,  in 
•consequence  of  the  very  large  electrode  surfaces  close  to  each 
•other. 

The  instrument  was  first  described  by  Bibs  and  Schonherr2 
who  used  it  upon  the  advice  of  Oettel  in  their  work  upon  the 
formation  of  persulphuric  acid.  At  that  time  Oettel  used  a 
Tectangular  glass  trough  with  three  electrodes,  i.  e.,  one  anode 

1  R.  Lorenz:  Elektrochemisches  Praktikum,  1901,  13. 

2  Elbs  &  Schonherr:     Studien  iiber  die  Bildung  von  Uberschwefelsaure. 
Zeitschr.  fur  Elektrochem.,  1894-1895,  469. 


94 


ELECTROLYSIS   OF  WATER. 


Fig.  74- 

and  two  cathodes.  The  anode  has  a  double  surface  of  about 
80  sq.  cm.,  the  cathodes  a  somewhat  greater  surface  on  the 
one  side. 

The  experimenters  write  as  follows  concerning  their  inves- 
tigations with  this  Oettel  voltameter  when  using  alkaline  so- 
lution. 

"  The  alkaline  voltameter  furnishes  mixed  gas  free  from 
ozone.  Even  with  a  current  of  3  amperes  the  instrument 
warmed  up  only  very  slightly,  while  in  the  acid  voltameter 
with  this  current  the  temperature  rose  quickly  to  50°  C.  If 
the  acid  voltameter,  as  is  the  case  in  many  constructions,  pos- 
sesses a  small  space  for  containing  the  sulphuric  acid,  the  lat- 
ter enriches  itself  after  being  used  for  a  short  time  in  conse- 
quence of  the  loss  of  water  (partly  also  by  the  decomposition 
of  water),  and  soon  reaches  such  a  concentration  that  the  for- 
mation of  persulphuric  acid  commences.  This  produces,  nat- 
urally, a  corresponding  loss  in  oxygen ;  the  sulphuric  acid 
formed  goes  over  to  the  cathode  and  is  there  reduced  so  that 
a  loss  of  hydrogen  also  results.  The  amount  of  gas  evolved 
will  in  consequence  be  considerably  less  than  the  quantity  re- 
quired by  Faraday's  law,  if  the  filling  up  with  water  is  not  at- 
tended to  carefully  and  at  the  proper  time.  An  experiment 


PROCESSES   AND   APPARATUS. 


95 


confirmed  this  completely.  If  the  acid  voltameter  is  filled 
with  acid  of  1.4  specific  gravity,  and  is  connected  at  the  same 
time  with  an  Oettel  instrument  in  the  same  circuit  there  will 
l>e  obtained  in  the  former,  with  a  current  strength  of  y2  am- 
pere, 93.9  per  cent,  of  the  gas  obtained  in  the  latter;  with  i 
ampere  89.4  per  cent.,  with  2  amperes  87  per  cent.,  3  am- 
peres at  first  87  per  cent,  then  90.8  per  cent.,  and  still  later 
93.6  per  cent.  The  rise  of  the  percentage  with  the  last  cur- 
rent strength  is  explained  by  the  rise  of  the  temperature  of 
the  voltameter  to  a  condition  of  equilibrium  in  the  last  case 
and  at  high  temperatures  the  formation  of  persulphuric  acid 
•diminishes.  Using  the  acid  of  specific  gravity  of  1.15,  the  acid 
voltameter  gave  very  accurate  results.  The  test  was  made  by 
a  current  of  3  amperes  corresponding  to  a  current  density  of 
4  amperes  per  sq.  cm. 

The  above  averages  are  shown  in  the  following  table  : 

TABI,E  vi. 


Current 
strength. 

Tension. 

Current  den- 
sity per  sq.  cm. 

Remarks. 

0.2  amperes 

0.5 
0.92 
2.42       " 
4.21 

1.85   volts 
I.98        « 
2.09        " 
2.32 

2-55       " 

0.25  amperes 
0.62       " 
1.15       " 
3.02       " 
5-26       « 

The  ordinary  voltameter  filled  with 
sulphuric  acid  (with  an  anode  sur- 
face of  7  sq.  cm.)  required  on  the 
other  hand  3  to  3.  5  volts  tension. 

VOLTAMETER  OF  WAITER-NEUMANN. 

The  voltameter  of  Walter-Neumann  (Fig.  75)  consists  of  a 
glass  bulb,  to  which  is  attached  a  graduated  glass  tube  with  a 
glass  stop-cock  and  funnel.  The  bulb  contains  the  two  plati- 
num electrodes,  which  are  connected  with  the  source  of  cur- 
rent by  platinum  wires  sealed  through  its  sides.  A  rubber 
connecting  tube  communicates  with  the  straight,  ungraduated, 
glass  tube  carried  by  the  same  stand. 

In  using  the  instrument  the  filling  tube  is  raised  with  the 
stop-cock  of  the  graduated  tube  left  open  until  the  acidulated 
water  fills  the  latter,  upon  which  the  stop-cock  is  closed  and 
the  current  turned  on.  Working  in  this  way,  the  irregular 
interval  at  the  beginning  of  electrolysis  falls  within  the  time 


96 


ELECTROLYSIS   OF   WATER. 


.  75- 


Fig.  76. 


of  the  experiment.  More  accurate  results  are  obtained  if  the 
filling  tube  is  left  with  stop-cock  open  until  the  electrolyte  in 
the  graduated  tube  stands  at  the  upper  °  point,  and  the  cur- 
rent then  be  turned  on,  the  cock  being  still  open,  and  the  lat- 
ter only  closed  when  the  current  has  reached  a  constant  value,, 
and  the  time  of  the  experiment  reckoned  from  this  instant.. 
During  the  electrolysis  the  filling  tube  is  constantly  lowered 
so  that  the  level  of  the  liquid  in  the  graduated  tube  and  the 
filling  tubes  are  at  the  same  height  at  the  end  of  the  experi- 
ment for  the  purpose  of  making  the  reading.  The  two  glass 
tubes  should  be  of  nearly  the  same  section  in  order  to  equalize 
the  effect  of  capillarity,  which  is  scarcely  noticeable  except  in. 
too  narrow  tubes. 

Fig.  76  shows  a  voltameter  on  the  same  principle.     It  is 
distinguished  by  having  the  funnel  closed  by  a  ground  stopper 


PROCESSES   AND   APPARATUS. 


97 


carrying  a  thermometer,  and  the  leveling  of  the  fluid  in  the 
two  tubes  is  made,  not  by  lowering  the  filling  tube  but  by 
drawing  off  the  electrolyte.  The  support  carries  an  adjust- 
able mark  for  indicating  the  level.  It  is  not  possible  with  this 
apparatus  to  equalize  irregularities  at  the  beginning  of  the 
electrolysis. 

VOLTAMETER  OF  BERTIN. 

The  voltameter  of  Bertin  employs  the  hydrogen  alone  for 
the  measurement.  It  consists 
of  a  graduated  burette,  con- 
nected at  its  upper  end  by  a 
capillary  tiibe  with  a  glass 
bulb.  The  latter  carries  a 
hose  connection  in  order  to 
be  able  to  draw  electrolyte 
into  the  burette.  The  burette 
dips  into  a  vessel  which  con- 
tains the  two  platinum  elec- 
trodes, of  which  only  the  neg- 
ative one  reaches  into  the  bu- 
rette. The  capillary  tube 
hinders  the  rise  of  gas  bub- 
bles into  the  gas  bulb,  so 
that  the  evolved  hydrogen 
can  be  read  off  directly.  The 
equalizing  of  the  level  of  the 
liquids  is  done  by  the  proper 
immersion  of  the  burette. 
As  far  as  concerns  the  irreg- 
ularities at  the  beginning  of 
the  experiment,  the  same 
suggestions  apply  to  this  as 
to  the  previous  arrange- 
ments. 


Fig-  77- 


98 


ELECTROLYSIS   OF   WATER. 


VOLTAMETER  OF  MINET. 

Two  voltameter  constructions  of  Minet1  are  different  from 
those  already  described.  One  arrangement,  which  is  shown 
in  Figs.  77-80,  is  intended  to  avoid  the  sources  of  error  in  the 
mixed  gas  voltameter,  such  as  absorption  of  gas  and  secondary 
reactions. 

The  apparatus  consists  of  two  principal  parts.     In   the  up- 


.  78.  Fig.  79.  Fig. 

per  right-hand  part  are  two  decomposing  vessels,  CtC2,  which 
communicate  with  each  other  by  the  three-way  stop-cock  R2. 
To  the  left  are  two  communicating  tubes.  The  tube  t  is 
graduated  and  is  in  combination  with  the  decomposing  space 
Cx,  by  means  of  the  narrow,  bent  tube  O  Ot.  The  electrolyte 
is  poured  in  through  the  rilling  tube  connected  with  the  de- 
composing vessel  C2,  in  charging  which  the  stop-cock  R2  has 
the  position  shown  in  Fig.  78  and  the  stop-cock  Ri?  is  left 
open.  The  electrolyte  is  run  in  to  the  marks  Ox  Oa.  Then 
the  tubes  IF  are  filled  to  the  marks  O  O1,  during  which  the 
the  stop-cock  Rt  is  left  open  and  R3  is  closed.  The  latter  has 
the  object  of  exact  adjustment  of  the  level  in  the  communi- 
cating tubes. 

At  the  beginning  of  the  electrolysis  the  electrolyte  must  be 
exactly  adjusted  to  the  marks  O1  O  Ox  Oa.  Fig.  80  shows  the 
position  of  the  three-way  cock  R2  as  soon  as  the  electrolyte  is 
to  be  replaced  for  another  measurement. 

1  Trait^  th£oriqueet  pratique  d'Electro-Chimie,  1900,  353. 


PROCESSES  AND   APPARATUS. 


99 


The  decomposing  vessel  C2  contains  only  one  electrode  Aa, 
while  the  decomposing  space  C,  contains  two  of  them  A  and 
Aj.  This  arrangement  allows  either  mixed  gas  or  oxygen  or 
hydrogen  to  be  caught  as  desired.  The  determination  is  only 
made  when  the  current  has  become  constant.  This  is  quickly 
reached  when  the  source  of  current  has  a  sufficiently  high 
electromotive  force,  and  its  strength  is  correspondingly  regu- 
lated by  a  rheostat. 

During  the  beginning  of  the  electrolysis  the  stop-cock  Rt 
remains  open.  Closing  the  same  is  the  beginning  of  the  ex- 
periment, opening  the  switch  is  the  end .  The  equalizing  of  the 
pressure  in  if,  necessary  for  reading  the  gas  volume,  is  done 
by  the  manipulation  of  the  dropping  stopper  R3.  The  water 
used  is  saturated  with  oxygen  and  hydrogen  before  the  ex- 
periment and  is  acidulated  with  0.5  per  cent,  sulphuric  acid. 

According  to  Minet's  researches,  which  are  in  part  repro- 
duced in  the  following  table,  the  method  of  working  described 
is  suitable  only  for  currents  under  0.5  ampere. 

TABLE  VII. 
Calibration  of  a  galvanometer.     Inner  resistance  at  18°  C.  =  17.1  Ohms. 


Inserted 

Currents  trength 

Current  strength 
in  the 

Number  of 

Galvanometer 
constant. 

resistance. 

in  the  voltameter. 
J 

galvanometer. 

divisions. 
n 

*  =  ! 

n 

Ohm. 

Ampere. 

Ampere. 

— 

Ampere. 

00 

0.00369 

0.00369 

9-65 

0.000382 

<  < 

0.00859 

0.00859 

22.50 

0.000382 

'  ' 

0.01464 

0.01464 

38-50 

0.000380 

4.00 

0.07608 

0.01415 

37.00               0.000382 

" 

0.0997 

0.01897 

49.80               0.000381 

o.  1098 

0.02097 

55-00 

0.000381 

°-734 

0.1197                  0.00496 

13.00 

0.000381 

'  ' 

0.1206                  0.00498 

13.00 

0.000383 

2.OO 

0.1206                  0.01272 

33-00 

0.000385 

0-734 

0.1585                  0.00656 

17.00 

0.000386 

11 

0.^79                   0.01155 

30.00 

0.000385 

'  ' 

0.417                    0.01722 

45.00 

0.000382 

i  < 

0.466                   0.01925 

50.00 

0.000385 

<  < 

0.557                   0.02296 

60.00 

0.000383 

Minet  claims  for  his  apparatus  the  following  : 

(i)  The  decomposing  spaces  are  independent  of  the  rest  of 

the  apparatus.     Their  volume  can  be  reduced   at  pleasure. 

The  electrolyte  is  therefore  quickly  saturated  with  gas. 


100  ELECTROLYSIS   OF   WATER. 

(2).  If  the  pressure  is  kept  constant  during  the  experiment 
by  manipulating  the  stop-cock  RS  there  need  be  no  fear  that 
the  volume  read  off  will  be  too  large  by  reason  of  the  setting 
free  of  absorbed  gas. 

(3).  The  volume  of  the  tube  between  O  Ox,  is  so  small  that 
no  correction  is  necessary  for  differences  of  temperature.  . 

(4).  The  graduated  tube  /  consists  of  several  parts:  Of  two  en- 
largements (P  Px)  of  different  content,  and  a  straight  tube  which 
is  divided  in  o.oi  ccm.  The  divisions  are  2  mm.  apart.  The 
enlargements  allow  the  measurement  with  the  one  apparatus 
of  widely  varying  current  strengths  without  giving  to  the 
graduated  tube  abnormal  dimensions. 

(5).  Since  t  and  tf  are  of  like  calibre,  no  correction  is  neces- 
sary because  of  capillarity. 

Using  electrolytes  with  0.5  per  cent,  sulphuric  acid  and  a  cur- 
rent strength  below  0.5  ampere,  there  is  no  loss  by  the  for- 
mation of  ozone,  hydrogen  dioxide,  or  persulphuric  acid,  as 
well  as  no  loss  of  hydrogen  noticeable  by  reduction  of  these 
products.  These  accessory  phenomena  only  begin  with  a 
higher  acid  concentration  and  a  greater  current  strength. 

VOLTAMETER  OF  MINET  FOR  INDUSTRIAL  PURPOSES. 

Minet's  voltameter  for  industrial  purposes1  rests  on  another 
principle  of  construction. 

In  this  arrangement  the  increase  of  pressure  upon  an  en- 
closed volume  of  gas  is  measured. 

A  glass  vessel  with  a  contraction  O,  as  in  Fig.  81,  stands  in 
combination  with  a  manometer  M,  which  is  constructed  to 
stand  a  pressure  of  two  atmospheres  and  allows  reading  to 
i/ioo  of  an  atmosphere.  A  is  a  tube  which  may  be  her- 
metically closed  and  through  which  the  electrolyte  may  be 
poured  in. 

The  lower  compartment  of  the  glass  vessel  contains  the 
electrolyte,  the  level  of  which  is  raised  at  the  commencement 
of  each  measurement  to  the  mark  O  so  that  the  upper  part 
of  the  apparatus  always  contains  the  same  gas  volume  V. 

1  A.  Minet:  Traite  theorique  et  pratique  d'Electrochemie,  1900,  357. 


PROCESSES   AND    APPARATUS. 


101 


Fig.  81. 

The  increase  of  pressure  shown  by  the  manometer  is 

/  =  Ktz, (i), 

in  which  v  is  the  volume  of  the  gas  evolved  during  the  meas- 
urement reduced  to  normal  atmospheric  pressure  P;  Kx  is  a 
coefficient  depending  upon  the  volume  V  and  the  pressure  P. 
Therefore  we  have 


and 


on  the  assumption  that  the   temperature  during  the  experi- 
ment remains  constant. 

Since,  on  the  other  hand,  the  volume  V  of  the  gas  evolved 
is  proportional  to  the  current  strength  Q,  therefore 


102  ELECTROLYSIS   OF   WATER. 

and  putting  for  v  its  value  from  the  first  equation,   we  have 

P 


Q  = 


KK 


and  if  we  place  ^  ^   =  K,  we  have  Q  =  K./  ;  that  is,  the  cur- 

12 
rent  strength  going  through  the  galvanometer  is  proportional 

to  the  pressure  shown  by  the  manometer. 

The  coefficients  KxK2  which  limit  the  value  K  can  be  cal- 
culated if  we  know  the  pressure  at  the  start,  and  the  tempera- 
ture, which  is  taken  as  constant  for  the  duration  of  the  ex- 
periment. 

Usually  the  coefficient  K  is  determined  experimentally  by 
a  comparison  of  the  manometer  results  with  those  of  a  cor- 
rectly calibrated  galvanometer,  and  correctly  measuring  the 
time  of  the  electrolysis. 

The  voltameter  naturally  gives  accurate  readings  only  when 
the  temperature  and  pressure  are  the  same  as  when  the  instru- 
ment was  calibrated.  But  since  the  temperature  in  laboratories 
varies  very  little  and  the  atmospheric  pressure  seldom  more 
than  i  per  cent,  above  and  below  the  normal,  the  instrument 
is  sufficiently  exact  for  a  series  of  practical  tests  with  small 
current  strength  ;  for  example,  for  rough  electro-analytical 
work  where  it  can  be  used  likewise  as  a  current  meter. 

For  a  volume  of  V  —  1500  ccm.  and  an  allowable  increase 
of  pressure  of  3  atmospheres,  the  instrument  will  register 
4-5  ampere  hours. 

(£)  For  Technical  Purposes. 
Process  of  Eldridge,  Clark  and  Blum,  1898. 

For  the  technical  manufacture  of  mixed  gas  (oxy-hydrogen 
gas)  we  know  of  only  one,  that  of  Eldridge,  Clark  and  Blum, 
U.  S.  patent,  603,058. 

We  have  not  heard  of  the  practical  application  of  this  pro- 
posal, and  since  such  is  hardly  to  be  expected,  it  will  suffice 
if  we  here,  'for  the  purpose  of  completeness,  reproduce  extracts 


PROCESSES   AND   APPARATUS. 


103 


from  the  patents  which  have  appeared  in  the  technical 
journals.1 

The  whole  arrangement  is  shown  in  Figs.  82-84. 

A  steel  cylinder,  2,  provided  above  and  below  with  flanges, 
5  and  6,  is  lined  inside  as  thickly  as  possible  with  a  coating, 
70,  of  graphite  or  some  difficultly  fusible  material.  The  bot- 
tom of  the  space  inside  is  formed  of  the  carbon  cathode  7j, 


Fig.  82. 

fastened  tightly  to  the  steel  floor-plate  j.  The  latter  arrange- 
ment is  held  tightly  down  upon  two  stoneware  plates,  8  and  p, 
by  bolts  7.  There  are  diametrically  opposite  openings,  77  and 
12,  through  the  two  walls  of  the  cylinder,  the  first  for  leading 
in  water  and  the  last  for  discharging  the  gas  formed.  The  inside 

of  the  cylinder  is  closed  air-tight  by  a || shaped    cover 

made  tight  by  an  asbestos  gasket,  /<?,  and  screwed  down  by  the 
bolts  77  to  the  flange  6.  The  carbon  anode  14  projects 
through  the  prolongation  19  of  the  cover,  insulated  by  means 
of  asbestos  and  loam.  A  metal  cap,  20,  is  screwed  also  upon 
the  prolongation  and  likewise  insulated  by  the  mixture  at  22 
to  24.  The  upper  end  of  the  anode  is  fastened  in  a  clamp, 
25-24! ,  which  runs  on  a  rack,  ^7.  The  latter  is  movable  ver- 
tically by  a  spur-wheel,  j7,  held  in  a  frame,  28,  having  on  its 

1  Zeitschr.  f.  Elektrochem.,  1898-1899,  246. 


IO4 


ELECTROLYSIS    OF   WATER. 


axle  an  insulated  handle,  32.  The  rack  and  the  frame  rests  on 
a  stand,  29-30',  which  is  screwed  down  upon  the  flange  6  of 
the  cylinder  by  means  of  the  insulating  rings  j#,  jp  by  two 
clamps,  40-41.  The  electric  current  is  introduced  by  the 
wires  35—42  held  fast  by  the  screws  36,  43.  The  electrodes 


30'- 


Figs.  83  and  84. 

are  brought  into  contact  with  each  other  and  after  the  for- 
mation of  an  arc,  slightly  separated.  Then  the  pump  45 
through  the  conductors  46-49'  forces  water  from  the  holder 

49  through  //  into  the  interior  of  the  cylinder  where,  in  con- 
sequence of  the  heat  from  the  arc,  the  water  is  decomposed  and 
goes  off  as  mixed  gas  through   12.     A  part  of  the  oxygen, 
however,  combines  with  the  carbon  of  the  electrodes  to  form 
carbon  dioxide.     The  gas  mixture  is  led  off  to  the  gasometer 

50  through  the  valves  53-56.     A  large  part  of  the  carbon  di- 


PROCESSES    FOR    EVOLUTION   OF   OXYGEN.  105 

oxide  is  there  absorbed  by  waste  water.  The  whole  apparatus 
is  so  built  that  the  single  pieces  (cylinder,  gasometer,  etc.)  are 
easily  taken  apart  and  transportable. 

C.  Processes  for  the  Simple  Evolution  of  Oxygen. 

(a]  Through  Depolarization  at  the  Cathode. 

Many  have  attempted  to  produce  pure  oxygen  by  the  elec- 
trolysis of  water  without  the  use  of  diaphragms,  by  using  de- 
polarizing cathodes  to  absorb  the  hydrogen  through  a  redu- 
cing reaction. 

Process  of  Coehn,  1893. 

Of  these  attempts,  most  attention  has  been  given  to  that  of 
Dr.  A.  Coehn,  German  patent  75,930,  of  the  i4th  of  July, 
1893. 

PATENT   CLAIM. 

"An  apparatus  for  the  electrolytic  production  of  oxygen 
and  the  halogens,  characterized  by  the  use  of  a  cathode  con- 
sisting of  metal,  and  capable  of  absorbing  hydrogen  in  order 
that  the  same  may  be  used  in  a  primary  or  secondary  element 
for  the  generation  of  the  electric  current." 

DESCRIPTION. 

In  wording  this  claim  so  generally,  Coehn  had  especially 
in  mind  the  use  of  negative  accumulator  plates  as  cathodes. 
These  absorb,  as  they  do  in  the  ordinary  charging  of 
accumulators,  the  hydrogen  set  free  at  their  surface  up  to  a 
certain  saturated  point,  which  is  recognized  by  the  strong 
evolution  of  free  hydrogen.  These  cathodes  loaded  with 
hydrogen  are  then  to  be  used  in  a  primary  or  secondary  ele- 
ment as  electrodes,  whose  rnake-up  is  adjusted  to  the  local 
conditions.  Coehn  instances  an  element  of  the  Daniell  type, 
in  which  the  Pb-H  electrode  replaces  the  zinc  and  is  sepa- 
rated from  the  copper  in  the  copper  sulphate  solution  by  a 
diaphragm.  Coehn  also  proposes  single  fluid  cells,  such  as 
Pb-H.  against  carbon  or  copper  in  sulphuric  acid.  Polariza- 


106  ELECTROLYSIS   OF   WATER. 

tion  is  to  be  avoided  by  a  rapid  circulation  of  the  sulphuric 
acid  or  by  blowing  in  air.  The  work  done  by  the  current 
furnished  by  these  elements  is  to  partially  supply  the  current 
necessary  for  the  production  of  oxygen. 

The  apparatus  has  not  found  application  in  practice 
since  it  is  indeed  difficult  to  stick  close  to  the  border  where 
the  cathode  plate  shall  be  properly  utilized  and  yet  no  hydro- 
gen be  evolved  from  it.  One  is  also  not  sure  of  not  obtaining 
an  explosive  gas  mixture.  Besides  that,  the  partial  recovery 
of  the  energy  by  the  precipitation  of  copper  out  of  cop- 
per sulphate  in  the  Daniell  cell  would  indeed  be  too  expen- 
sive for  technical  purposes. 

COPPER   OXIDE   CATHODES. 

It  is  self-evident  also  that  copper  oxide  cathodes  may  be 
used  as  depolarizers  for  the  electrolytic  obtaining  of  oxygen. 

The  property  of  the  copper  oxide  cathode  of  being  easily 
regenerated  is  an  advantage,  but  such  an  arrangement  has, 
however,  the  disadvantage,'  as  against  the  Coehn  proposition, 
of  a  small  mechanical  strength  of  the  oxide  plate,  and  the  dis- 
agreeable work  of  handling  concentrated  alkaline  solutions. 

In  the  technical  operation  of  the  process  thus  briefly  de- 
scribed, great  difficulties  are  to  be  expected  in  the  control  of 
the  operation,  which  obstacles  will  outweigh  the  attempted 
economy  in  energy.  (  j 

Process  of  Haberrriann,  1892. 

Habermann1  studied  likewise  the  different  methods  of  ob- 
taining oxygen  by  electrolysis.  The  occlusion  of  hydrogen 
by  palladium  demonstrated  its  in  applicability  for  the  manu- 
facture of  large  quantities  of  oxygen.  Better  results 
were  obtained  with  a  solution  of  potassium  permanganate 
acidulated  with  sulphuric  acid.  According  to  Habermann's 
results  the  use  of  a  solution  of  potassium  chromate  acidu- 
lated with  sulphuric  acid  is  the  most  suitable.  If  the 
solution  contains  20  per  cent,  potassium  chromate,  no 
evolution  of  hydrogen  takes  place.  No  probability  of  the  tech- 

1  Zeitschr.  f.  ang.  Chemie,  1892,  323-328. 


PROCESSES   FOR   EVOLUTION   OF   OXYGEN.  1 07 

tiical  utilization  of  this  process  can  be  entertained  in  view  of 
the  high  price  of  the  raw  materials. 

(£)  By  the  Precipitation  of  Metal  at  the  Cathode. 

The  obtaining  of  oxygen  in  the  electrolytic  way  is  possible 
by  decomposing  metallic  oxide  salts,  using  insoluble  anodes 
and  simply  precipitating  the  metal  out  electrolytically.  This 
metal  must  naturally  be  such  as  to  be  separated  out  in  thick 
layers  of  precipitate  with  a  good  efficiency  and  without  the 
formation  of  hydrogen  or  with  very  little  of  that  gas.  On 
this  assumption  quite  a  series  of  metals  as  zinc,  nickel,  etc., 
are  used. 

PRECIPITATION    OF   COPPER. 

Copper  fills  the  conditions  the  nearest,  but  when  using  this 
metal  a  very  careful  control  of  the  operation  is  necessary  in 
order  to  use  up  the  electrolyte  as  far  as  possible,  and  on  the 
other  side  the  conditions  in  price  between  the  metal  precipi- 
tated and  the  metallic  salt  from  which  it  is  taken,  works 
against  the  industrial  application  of  the  process  ;  and  finally, 
since  the  solution  cannot  be  entirely  freed  from  the  metal  and 
the  saturation  of  the  solution  with  oxide  costs  still  more, 
there  results  a  worthless  dilute  solution  of  the  corresponding 
free  acid  in  which  the  remainder  of  the  metallic  salt  is  still 
contained.  Hoffer1  recommends  for  laboratory  purposes  the 
electrolysis  of  copper  sulphate  solutions  with  insoluble  anodes, 
producing  oxygen.  The  electrodes  are  of  different  sizes;  the 
current  density  at  the  cathode  is  as  small  as  possible,  at  the 
anode  as  large  as  possible. 

The  industrial  application  of  the  methods  mentioned  in 
this  group  is  not  to  be  expected  for  the  purpose  of  the  manu- 
facture of  electrolytic  oxygen. 

CHRONOLOGICAL  REVIEW. 

Having  now,  on  the  previous  pages,  mentioned  almost  all  of 
the  electrolytic  processes,  some  of  which  have  only  been  pro- 

1  Math.-naturw.    Ber.  aus  Ungarn,   Bd.   I  u.   2.  —  Ber.  der  deutschen 
chem.  Ges.,  22,  168.  —Die  chemische  Industrie,  12,  200. 


1 

= 

Date. 

Name. 

Patent. 

Connection. 

3 
fc 

Place. 

Number. 

Date. 

I 

1885 

D'Arsonval 







Single  pole 

2 

1888 

D.  I^atchinoff 

Germany 

51998 

Nov.  20,  1888 

Single  pole 





— 

Double  pole 

3 

1888 

Ducretet 





— 

Single  pole 

4 

1888 

Renard 





— 

Single  pole 

5 

1890 

Delmard 

Germany 

52282 

Nov.  23,  1890 

Single  pole 

6 

1892 

Habermann 







Single  pole 

7 

i893 

Dr.  A.  Coehn 

Germany 

75930 

July  14,  1893 

Single  pole 

8 

i893 

Bell 

Germany 

78146 

Oct.  30,  1893 

Single  pole 

9 

1893 

Garuti 
Garuti  &  Pompili 
Societe  1'Oxyhy- 

Germany 
England 
U.  S.  A. 

83110 
16588/93 
534295 


Aug.  5,  1893 
Feb.  19,  1895 

Single  pole 

Germany 
England 
U.  S.  A. 

83097 
23663/96 
629070 

March  6,  1897 
July  18,  1899 

Germany 
England 

106226 
12950/900 

Feb.  16,  1898 
Oct.  24,  1900 

10 

i893 

Siemens  Brothers 
&  Co.  and  Obach 

England 

"973/93 

April  21,  1894 

Single  pole 

ii 

1894 

E.  Ascherl 

Austria 

44/5862 

Sept.  26,  1894 

Single  pole 

12 

1896 

El.  A.  G.  formerly 
Schuckert  &  Co. 

Germany 

G.  M.i 

80504 

Sept.  19,  1896 

Single  pole 

13 

1898 

Hazard-Flamand 

Germany 

10^499 

June  12,  1898 

Single  pole 

14 

1898 

Eldridge,  Clarke 
and  Blum 

U.  S.  A. 

603058 



Single  pole 

15 

1899 

Dr.  O.  Schmidt 

Germany 

111131 

June  13,  1899 

Double  pole 

16 

1899 

P.  J.  F.  Verney 

France 

280374 



Single  pole 

17 

1900 

M.  U.  Schoop 

Germany 
Austria 

G.  M.i 

141049 

1285 

Sept.  5,  1900 
1900 

Single  pole 

i 

1  Registered  design. 


Method  of 
separation  of 
the  gases. 

Separating 
material.  » 

Electrodes. 

Current 
density 
amperes 
per  sq.  cm. 

Working 
electromo- 
tive force. 
Volts. 

Electrolyte. 

Products  of 
decomposition 

+ 

- 

Porous 
diaphragm 

lyinen  or  cotton 

Iron 

2 

? 

30$  KOH 

O 

H2 

Porous 
diaphragm 

Asbestos  cloth 

Iron 

3-5 

2-5 

10$  NaOH 

O 

H2 

+  I<ead 
—  Carbon 

10-15$  H2SO4 

Parchment  paper 

Iron 

10.0 

10$  NaOH 

Porous 
diaphragm 

Asbestos  cloth 

Iron 

? 

? 

Alkaline 

O 

H2 

Porous 
diaphragm 

Asbestos  cloth 

Iron 

? 

2.7-3.0 

13$  NaOH 

O 

H2 

Porous 
diaphragm 

Asbestos  cloth 

Iron 

f 

? 

Alkaline 

O 

H2 





Platinum 

? 

? 

20$  K«CrO4  + 
H2S04 

O 







Lead 

? 

? 

H2S04 

0 



Porous 
diaphragm 

Asbestos  cloth  and 
vegetable  fibres 

Iron  with 
granules 

? 

? 

15$  NaOH 

O 

H2 

Conducting 
partitions 

I<ead 

Lead 

2-4 

2-45-3 

12$  H2SO4 

O 

H2 

Sheet  iron  with  a 
zone  of  perfora- 
tions beneath 

Iron 

2 

NaOH,  21°  B. 
or 
KOH  i6-i8°B. 

Sheet  iron  with  a 
zone  of  perfora- 
tions in  the  middle 

Conducting 
partitions 

Iron  wire  netting 

Iron 

? 

2-5 

Alkaline 

O 

H2 

Impermeable 
bells 

Glass 

Silver  or 
platinum 
wire 

? 

? 

Dilute  H2SO4 

O 

H2 

Impermeable 
partitions 

Insulating 
material 

Iron 

? 

2.8-3.0 

15$  NaOH 

0 

H2 

Non-conduct- 
ing gutters 

Non-conducting 
material 

Metal 

? 

? 

? 

O 

H2 

None 

None 

Carbon 

? 

Arc 

Water 

0  + 

H2 
H2 

Porous 
diaphragm 

Asbestos  cloth 

Iron 

About  2 

2-5 

10$  K2C03 

O 

Non-conduct- 
ing gutters 

Non-conducting 
material 

Iron 

? 

? 

NaOH 

O 

H2 

Impermeable 
tubes 

Glass  or  clay 

Iron 

? 

2.25 

Alkaline 

O 

H2 

Hard  lead 

3-6-3-9 

H2S04  D-  1.235 

110  ELECTROLYSIS   OF   WATER. 

posed,  others  really  introduced  into  practice,  Table  VIII 
(pages  preceding)  has  been  constructed  for  an  easy  review,  in 
which  the  processes  are  arranged  in  chronological  order,  ac- 
cording to  the  time  of  their  publication,  together  with  the 
most  important  characteristics  of  each. 

IV.   APPLICATIONS. 
General. 

From  the  previous  section  and  the  applications  which  were 
described,  it  may  be  assumed  that  the  question  of  the  indus- 
trial electrolysis  of  water  for  the  purpose  of  obtaining  oxygen 
and  hydrogen  has  been  solved  in  numerous  ways,  regarded 
from  the  standpoint  of  technical  construction.  Also  improve- 
ments in  the  apparatus  and  processes  are  necessarily  not  ex- 
cluded, yet  they  will  in  no  case  hereafter  be  of  such  comprehen- 
siveness as  to  affect  the  question  of  the  applicability  of  the 
technical  electrolysis  of  water.  On  the  other  hand,  as 
Schmidt  has  opportunely  remarked  in  one  of  his  lectures, 
the  applicability  of  such  processes  has  become  much  more  of 
a  practical  question  for  discussion  since  the  recent  develop- 
ments in  the  line  of  cheap  power,  and  the  improvements 
which  have  been  made,  particularly  in  the  carbon  dioxide  in- 
dustry in  the  storage,  compression,  and  transportation  of  gas. 

There  is  left  for  us  to  describe  separate  installations  of  the 
processes  of  the  above-mentioned  apparatus,  and  their  capa- 
bility of  competing  with  other  processes. 

Before  passing  to  these  we  will  bring  together  in  compact 
form  data  of  the  cost  of  plant  and  cost  of  operation  given  in 
the  description  of  the  various  processes. 

COST   OF   PLANT. 

(Only  the  cost  of  the  electrolyzers  is  taken  into  considera- 
tion.) 

From  this  presentation  it  is  seen  that  the  bipolar  connected 
Schmidt  apparatus  costs  more  for  plant,  especially  for  small 
plants,  than  the  single  pole  apparatus.  In  this  connection  it 


APPLICATIONS. 


Ill 


TABI,E  IX. 
(Cost  of  Plant  for  One  Kilowatt  of  Energy  Used.) 


Unit  size  of  apparatus. 

Price  in 

System. 

Price  in 
dollars. 

dollars  per 
kilowatt. 

Amperes. 

Volts. 

Kilowatts. 

Renard. 

365 

2.7 

0.98 

20.00 

20.50 

Schmidt. 

J5 

65 

0-975 

440.00 

45L25 

30 

65 

1-950 

600.00 

307.50 

60 

65 

3.900 

800.00 

205.00 

IOO 

65 

6.500 

IIOO.OO 

169.25 

150 

65 

9-750 

1800.00 

182.00 

15 

110 

1.65 

488.00 

298.00 

30 

1  10 

3-30 

700.00 

212.  OO 

60 

1  10 

6.60 

960.00 

145.50 

IOO 

no 

11.00 

1500.00 

136.25 

150 

IIO 

16.50 

2400.00 

I45-50 

15 

220 

3.30 

750.00 

227.25 

30 

220 

6.60 

1062.50 

161.00 

60 

220 

13.20 

1825.00 

'35-75 

IOO 

220 

22.00 

2680.00 

121.75 

150 

220 

33-oo 

4300.00 

130.25 

Schoop. 

175 

3-6 

0.63 

69.25 

109.75 

Garuti. 

400 

2-5 

1.  00 

p 

? 

Siemens   Bros,    and  > 
Co.  and  Obach.      j 

750 

3-0 

2.25 

187.50 

83-25 

El.  A.  G.,    formerly  ) 
Schuckert  and  Co.  ] 

600 

2-9 

1.74 

62.50 

36.00 

must  not  be  overlooked  that  with  bipolar  connections  a  con- 
siderable amount  will  be  saved  in  piping,  electrical  conductors, 
and  erection.  This  difference  is  most  easily  seen  when  we 
consider,  for  instance,  the  operation  of  the  plant  for  the  filling 
of  air  balloons.  A  normal  military  balloon  requires,  in  order 
to  be  filled  in  twenty-four  hours,  a  plant  of  about  200  kilowatts. 
To  do  this,  6  or  7  units  of  the  Schmidt  apparatus  of  the  largest 
type  will  be  necessary,  while  320  of  the  Schoop  electrolyzers,  200 
of  the  Garuti,  90  of  the  Siemens  Brothers  &  Obach,  and  115 
of  the  Schuckert  system  will  be  required.  We  have  left  out 


112  ELECTROLYSIS   OF   WATER. 

the  small  differences  in  the  operating  voltage,  since  we  wish 
to  make  only  a  rough  approximation. 

Further,  in  making  an  approximation  of  the  cost  of  plant 
we  must  take  into  consideration  the  fact  that  except  when 
very  large  plants  are  to  be  erected  in  which  a  sufficient  num- 
ber of  anodes  can  be  placed  in  series,  and  connected  to  an  or- 
dinary lighting  circuit,  the  single  pole  apparatus  otherwise  re- 
quires the  installation  of  a  particular  kind  of  low  voltage  and 
relatively  expensive  dynamo  machine  with  all  its  accessories. 

COST  OF  OPERATION. 

The  following  costs  of  operation  have  already  been  given 
for  the  various  processes  used  in  industrial  practice,  conclu- 
sions being  made  on  the  assumption  of  either  one  of  the  two 
or  the  mixed  gases  being  utilized. 

Along  with  the  cost  of  production  several  other  factors  may 
be  thought  of,  which,  under  some  conditions,  would  add 
materially  to  the  cost  of  operation. 

CONSUMPTION  OF  ANODES. 

One  question  would  be  the  using  up  of  anodes  when  work- 
ing with  iron  electrodes  in  alkaline  solutions.  The  view  of 
most  of  the  constructors  of  electrolytic  apparatus  for  the  de- 
composition of  water  that  the  corrosion  of  the  electrodes  may 
be  practically  neglected  because  of  the  "  passive  condition  " 
of  the  iron,  appears  not  to  be  completely  substantiated.  This 
question  was  discussed  in  connection  with  the  presentation  of 
the  Schmidt  apparatus  at  the  seventh  yearly  Assembly  of  the 
German  Electrochemical  Society  of  Zurich.  According  to 
the  communication  which  Heraeus  has  made  upon  the  basis 
of  the  operation  of  his  Schuckert  plant,  the  consumption  of 
anodes  is  not  unimportant.  Heraeus  supposed  the  cause  to  be 
primarily  in  the  presence  of  chlorine  and  sulphuric  acid  in 
the  cheap  caustic  soda  solution,  and  replaced  the  same  by  the 
purer  and  more  costly  caustic  potash, without,  however,  dimin- 
ishing the  consumption  of  the  iron  electrodes.  The  electrodes 
lasted  in  the  latter  case  as  in  the  former  about  one  year.  The 


APPLICATIONS. 


X. 


Cost  of  Producing  the  Gases  per  Cubic  Meter. 


System. 

Mixed  gas. 

Hydrogen. 

Oxygen. 

Remarks. 

Power  costing 

Power  costing 

Power  costing 

Kc. 

kilo- 
watt 
hour. 

Cents. 

I#C. 

per 
kilo- 
watt 
hour. 

Cents. 

*c. 

per 
kilo- 
watt 
hour. 

Cents. 

i#c. 
per 
kilo- 
watt 
hour. 

Cents. 

#c. 
per 
kilo- 
watt 
hour. 

Cents. 

i*c. 

per 
kilo- 
watt 
hour. 

Cents. 

A.  Pure  cost  of  power 
for    the    electrolysis 
without  compression. 
i    Schmidt       ... 

I.OOO 

0.900 

1.540 
1.050 
1.225 
1.325 

5.000 

4.500 
7-750 
5-250 
6.000 
6.750 

1.500 

1.325 
2.325 
1.540 
1.850 

2  025 

7.500 

6.750 
1.150 
7-750 
9.250 
1.025 

3.000 

2.750 
4-500 
3.000 
3-675 
4-075 

15.000 

13-500 
23.250 
15-500 
18.375 
20.400 

2.  Schoop  : 
(a)  alkaline  

(b)  acid 

4.  Siemens  &  Obach 

5- 

B.   Total  cost  of  produc- 
tion including  sink- 
ing fund  and  inter- 
est, but  without  com- 
pression. 
i    Schmidt       

7-775 
4.000 

5.000 
3-75° 

13-250 
11.500 

9.250 

11.250 
5.750 

7-500 
5-500 

19.250 
15.000 

13-500 

22.000 
11.750 

15.000 

II.OOO 

38.000 
1  30-500 

27.250 

Only  power  and  sink- 
ing fund  and  interest 
only  on  the  electro- 
lytic plant. 
Power    without    gen- 
eral expenses. 
Without  sinking  fund 
and  interest   on  the 
cost  of  gasometers, 
as  well    as    without 
general  expenses. 

2.  Schoop  (acid)  .... 

C.  Total  cost  of  produc- 
tion including  sink- 
ing fund,  interest, 
and  compression  of 
the  gases. 

28.750 
5-650 

35-5oo 

38.250 
8.500 

1 

47.000 

68.750 
14.500 

86.500 

Without  interest  and 
sinking  fund  on  the 
investment  in  flasks 
as  well  as  general 
expenses. 

electrolytic  formation  of  ferrates  may  also  indeed  be  assumed 
to  take  place,  which  explanation  Haber1  has  fixed  upon  re- 
cently as  the  result  of  his  extensive  study  of  the  subject. 

Schmidt  says,  on  the  contrary,  that  after  using  the  apparatus 
of  his  system  two  and  a  half  years,  the  electrodes  had  only  di- 
minished i  mm.  in  thickness.  It  is,  however,  to  be  remembered 

1  Zeitschr.  f.  Elektrochemie,   1900-1901. 


114  ELECTROLYSIS   OF  WATER. 

that  Schmidt  does  not  use  caustic  alkali,  but  potassium  car- 
bonate, which  is  very  free  from  sulphuric  acid  and  chlorine. 

ABSORPTION  OF  CARBON  DIOXIDE. 

A  further  alteration  may  take  place  in  the  charge  of  the 
electrolytic  apparatus  for  the  decomposition  of  water,  working 
with  caustic  alkaline  electrolytes,  which  is  due  in  part  to  the 
absorption  of  carbon  dioxide  from  the  atmosphere.  On  this 
point  it  is  to  be  remembered  that  the  most  modern  apparatus 
prevent  as  far  as  possible  the  contact  of  air  with  the  electro- 
lyte, in  which  a  layer  of  mineral  oil  upon  the  surface  of  the 
electrolyte  gives  good  service,  and  that  finally  with  apparatus 
working  at  high  temperatures  a  layer  of  vapor  above  the  elec- 
trolyte excludes  the  carbon  dioxide  of  the  atmosphere  in  a 
satisfactory  manner. 

SECURITY  FROM  EXPLOSIONS. 

Concerning  the  safety  of  the  gases  from  explosion,  the  limit 
of  safety  with  oxygen  lies  at  90-95  per  cent,  purity.  All  of 
the  newer  apparatus  are  completely  above  the  requirements  in 
this  respect. 

CONCURRENT   PROCESSES. 

Three  groups  of  processes  may  be  brought  out  as  competi- 
tors of  the  electrolytic  decomposition  of  water,  namely  : 

(1)  Other  electrochemical  processes  in  which  oxygen  or  hy- 
drogen are  obtained  as  by-products. 

(2)  Physical  processes. 

(3)  Purely  chemical  processes. 

(0  Electrochemical  Processes. 

(a)  Hydrogen. 

Hydrogen  is  the  most  important  of  the  by-products  of  elec- 
trochemical processes.  All  those  processes  which  rest  upon 
the  electrolytic  decomposition  of  the  alkaline  chlorides  evolve 
this  gas  in  important  amounts.  Of  these  processes,  those 
which  work  without  a  separation  of  the  electrode  spaces,  like 
the  manufacture  of  chlorates  and  hypochlorites  (usually  called 


ELECTROCHEMICAL   PROCESSES.  115 

electric  bleach),  hardly  permit  of  the  separate  utilization  of 
the  hydrogen,  since,  on  the  one  hand,  especially  with  electric 
bleach,  the  installation  is  mostly  too  small;  on  the  other  hand, 
with  both  classes  of  processes,  the  hydrogen  is  usually  con- 
taminated in  not  unimportant  quantities  with  the  products 
set  free  at  the  anode  (O,  Cl,  etc.).  In  those  processes,  on  the 
other  hand,  which  decompose  the  alkaline  chlorides  for  the 
purpose  of  manufacturing  separately  chlorine  and  caustic 
alkali,  hydrogen  can  be  obtained  in  the  pure  state.  In  such 
methods  of  working,  under  this  heading,  which  use  diaphragms 
for  instance  (processes  of  the  Elektron  companies),  the  catch- 
ing of  the  hydrogen  will  entail  not  very  convenient  altera- 
tions in  the  apparatus.  Such  methods  have,  as  a  rule,  at 
their  best,  the  cathode  spaces  only  fairly  tight.  To 
enclose  tightly  the  cathode  spaces  would  be  quite  incon- 
venient when  the  diaphragms  have  to  be  changed.  The  pos- 
sibility and  the  practicability  of  obtaining  hydrogen  as  a  by- 
product has  been  already  proven.  As  an  example,  the  Ver- 
einigten  Chemischen  Fabriken  Leopold  shall  sold  compressed 
hydrogen  which  had  been  obtained  as  a  by-product,  but  its 
production  has  since  been  given  up. 

The  obtaining  of  hydrogen  as  a  by-product  is  the  easiest 
with  those  electrolytic  alkali  processes  which  work  with  mer- 
cury cathodes.  The  amalgam  here  lies  in  a  space  distinct 
from  the  decomposing  apparatus,  and  so  only  this  space  need 
be  closed  air-tight  and  provided  with  suitable  piping. 

This  opportunity  brings  to  the  author's  remembrance  a  very 
interesting  application  of  the  hydrogen  set  free  by  the  de- 
composition of  this  amalgam.  He  had  at  one  time  the  occa- 
sion to  inspect  and  report  on  an  experimental  plant  at  Aachen 
run  on  the  Stormer  system.  Since  the  utilization  of  the 
hydrogen  was  not  to  be  thought  of  on  account  of  the  small- 
ness  of  the  plant,  Stormer  used  the  same  for  an  empirical  con- 
trol of  the  efficiency  of  the  apparatus.  The  hydrogen  escaped 
from  the  tightly  closed  amalgam  washing  apparatus  by  a  nar- 
row vertical  tube,  was  ignited  and  the  height  of  the  flame 
gave  an  approximate  idea  of  the  efficiency. 


Il6  ELECTROLYSIS    OP  WATER. 

Aside  from  the  manufacture  of  chlorates  and  electric  bleach, 
omitted  for  the  above  explained  reasons,  we  may  assume  the 
power  used  in  the  various  plants  which  are  concerned  with 
the  electrolytical  decomposition  of  alkaline  chlorides  at  in 
round  numbers  45,000  kilowatts.  If  we  assume  an  average 
current  output  for  all  competing  processes  at  80  per  cent.,  and 
the  average  working  voltage  of  4.5,  there  results  a  daily  pro- 
duction of  hydrogen  of  80,000  cubic  metres,  the  greater  part 
of  which  at  present  escapes  unused. 

There  is  therefore  no  prospect  of  success  for  the  electrolytic 
manufacturer  of  hydrogen  when  increasing  consumption  of 
the  chlorine  and  alkali  plants  permits  them  to  bring  their  by- 
product, hydrogen,  in  a  compressed  state  on  the  market. 
Those  cases  are  naturally  excepted  which  are  so  placed  with 
regard  to  a  hydrogen  market  that  the  transportation  of  the 
compressed  product  is  too  high  on  account  of  freight. 

(£)  Oxygen. 

Other  electrochemical  processes  scarcely  enter  as  competi- 
tors for  the  manufacture  of  electrolytic  oxygen.  There  is  in- 
deed a  possibility  that  oxygen  may  be  produced  as  a  by- 
product in  electrolytic  processes  working  with  insoluble 
anodes.  This  will,  however,  in  most  cases  be  obtained  with 
hydrogen  according  to  the  better  or  poorer  efficiency  of  the 
cathodic  precipitation. 

(2)  Physical  Processes. 

(a)  Oxygen. 

In  the  line  of  physical  processes,  the  Linde  method  of  ob- 
taining fluid  air  is  a  competitor  with  which  the  electrolytic 
manufacture  has  to  reckon.  According  to  Linde's  latest  com- 
munication1, he  is  in  a  position  to  produce  fluid  air  with  an 
expenditure  of  3  horse-power  hours  per  kilogram  with  his 
smaller  machines  or  with  his  largest  type  with  2  horse-power 
hours  per  kilogram,  and  believes  it  possible  to  reduce  the 
power  requirement  to  i  ^  horse-power  hour  per  kilogram. 

1  Zeitschr.  des  Vereins  deutscher  Ing.,  1900,  70. 


PHYSICAL   PROCESSES. 


117 


CO    SO     40     30     20     *>      0% 

Fig.  85. 


He  reckons  the  total  cost  of  liquid  air  with  large  plants  at 
2  J^  cents  per  kilogram.  These  assumptions  do  not  take  into 
account  the  large  losses  which  fluid  air  suffers  in  transporta- 
tion. 

The  possibility  of  fractioning  fluid  air  into  gas  mixtures  rich 
in  nitrogen  and  oxygen,  respectively,  is  well  known.  When 
the  separation  takes  place  at  atmospheric  pressure  the  re- 
sults are  as  shown  in  Fig.  85, 
as  given  by  Linde.  At  the  be. 
ginning  of  the  evaporation,  the 
gas  mixture  consists  of  about 
92  per  cent,  nitrogen  and  8 
per  cent,  oxygen.  This  relation 
changes  according  to  the  curve 
a  c  b,  on  different  evaporations. 
The  curve  d  e  shows  the  en- 
riching of  the  respective  values 

of  oxygen.  If  an  electrolytic  plant  utilizes  hydrogen  as  well 
as  oxygen,  it  can  compete  with  the  Linde  process  accord- 
ing to  the  costs  of  manufacture  so  far  given,  assuming  similar 
cost  prices  for  power,  because  the  electrolysis  requires  a 
smaller  investment  in  plant  and,  therefore,  a  smaller  sinking- 
fund  and  interest  cost.  The  conditions  are  not  so  favorable 
if  the  hydrogen  cannot  be  utilized.  The  figures  would  be 
still  further  to  the  advantage  of  Linde  if  the  hopes  of  this 
inventor  materialize  according  to  which,  by  utilizing  a  new 
principle  of  construction,  he  expects  to  make  one  cubic  metre 
of  gas  containing  50  per  cent,  of  oxygen  with  an  expenditure 
of  i  horse-power  hour.  In  such  a  case,  Linde  calculates  a 
total  cost  of  i  cubic  metre  of  gas  containing  50  per  cent,  of 
oxygen  at  0.625  cent>  which  is  equal  to  0.3  cent  per  horse- 
power hour. 

The  electrolytic  oxygen  would  be  able  to  compete,  without 
doubt,  in  all  those  cases  in  which  pure  gas  must  be  had,  since 
fluid  air  under  the  best  conditions  furnishes  a  mixture  contain- 
ing only  70-75  per  cent,  oxygen.  The  electrolytic  method 


Il8  ELECTROLYSIS   OF  WATER. 

would,  also,  according  to  all  probabilities  hold  the  field  for 
small  installations. 

(3)  Chemical. 
(a)  Hydrogen. 

The  purely  chemical  methods  for  obtaining  hydrogen  in- 
cludes solution  of  metals  in  acids  (iron,  zinc,  etc.).  The  elec- 
trolytic manufacture  is  technically  and  economically  superior 
to  these  processes  as  will  be  later  shown  more  in  detail. 

(£)  Oxygen. 

The  chemical  process  of  manufacturing  oxygen  which  rests 
upon  the  conversion  of  the  oxygen  of  the  air  into  chemical 
compounds  which  easily  give  up  their  oxygen,  such  as  the 
processes  based  on  barium  superoxide,  normal  plumbates,  so- 
dium manganates,  etc.,  furnish  only  an  impure  product  with 
about  85  to  90  per  cent,  oxygen,  and  what  has  been  said  of 
Linde's  fluid  air  in  this  respect  applies  also  to  them. 

The  processes  for  manufacturing  oxygen  from  compounds 
rich  in  oxygen  such  as  mercuric  oxide,  potassium  chlorate, 
manganese  dioxide,  potassium  chromate,  etc.,  are  not  really 
at  present  active  competitors  of  the  electrolytic  process. 

Compression. 

Concerning  the  compression  of  the  gases,  it  must  be  re- 
membered that  it  is  not  usually  carried  over  100  to  no  atmos- 
pheres and  only  in  extreme  cases  are  pressures  of  200  atmos- 
pheres used.  Schoop  gives  some  details  of  compression  plants 
in  his  recently  published  treatises.1  The  steel  flasks  are 
usually  made  to  contain  from  10  to  250  litres.  The  weight  is, 
on  the  average,  10  kilograms  to  a  cubic  metre  of  gas.  The  most 
practicable  sizes  of  flasks  are  shown  in  the  following  table 
taken  from  Schoop's  work : 

1  M.  U.  Schoop :  Die  industrielle  Elektrolyse  des  Wassers,  1901. 


SPECIAL  APPLICATIONS. 


119 


TABLE  XI. 


Length  in 
metres. 

Outer  diameter 
in  metres. 

Approximate 
weight  in  kilo- 
grams. 

Water  in  litres. 

Price  of  the  empty 
flasks  in  dollars. 

0.432 

0.076 

6 

1.40 

6.00 

0.609                        0.102 

II 

3.68 

6.75 

O.6OO 

0.140 

20 

7.00 

7.50 

0.930 

0.140 

20 

11.00 

8.25 

1.346 

0.140 

40 

16.70 

11.75 

I.O9O 

0.203 

45 

26.80 

15.00 

2.OOO 

0.205 

73 

50.00 

20.00 

Some  producers  of  oxygen  and  hydrogen  in  order  to  render 
certain  the  recognition  of  the  oxygen  and  hydrogen  flasks 
from  each  other,  provide  the  oxygen  flasks  with  right-handed 
valves  and  the  hydrogen  "flasks  with  left-handed  valves  and 
black  nozzles. 

Special  Applications. 

The  uses  of  oxygen  and  hydrogen  and  the  mixed  gases  are 
generally  known  and  will  here  be  collected  as  a  conclusion  of 
this  Monograph,  and  some  new  propositions  concerning  their 
use  alluded  to  more  at  length. 

(i)  Detonating  Gas. 

(0)    HIGH  TEMPERATURE. 

For  high  temperatures,  in  particular  the  working  of 
metals :  This  application  dates  back  to  the  work  of  St.  Claire- 
Deville  who  melted  platinum  in  the  oxyhydrogen  flame.  In 
many  cases  the  electric  furnace  can  be  replaced  by  the  oxy- 
hydrogen flame  and  in  this  connection  we  may  recall  the 
attempts  to  manufacture  calcium  carbide  without  the  electric 
current.  More  recently  the  question  of  using  mixed  gas  in 
glass  furnaces  has  regained  interest.  An  investigation  of 
Ascherl  has  been  in  this  direction.  The  manufacture  of  large 
glass  vessels  from  plates  of  glass,  melting  down  the  joints  with 
the  oxyhydrogen  flame,  is  carried  out  in  England  on  an  indus- 
trial scale. 

The  oxyhydrogen  flame  has  gained  an  important  place  in 
many  cases  in  the  working  of  metals  where  the  nature  of  the 


120 


ELECTROLYSIS   OF   WATER. 


metal  is  such  as  to  exclude  the  use  of  carbonaceous  gas  even 
when  mixed  with  oxygen.  A  content  of  carbon  either 
hinders  in  most  cases  the  soldering  entirely,  or  deteriorates 
the  quality  of  the  metal  soldered.  Repairing  of  water-tube 
boilers  can  be  easily  accomplished  with  an  oxyhydrogen  flame. 
We  shall  speak  of  the  soldering  of  lead  further  on  when 
treating  of  the  applications  of  hydrogen,  since  mixed  gas  is 
not  used  for  this  purpose  but  a  mixture  of  hydrogen  and 
oxygen  poorer  in  the  latter. 

(£)    LIGHTING. 

Lighting :  Mixed  gas  has  been  used  for  this  purpose  for  a 
long  time  for  the  so-called  Drummond  lime  light,  and  has 
attained,  for  special  purposes,  a  certain  sphere  of  usefulness, 
although  a  limited  one.  In  the  recent  Spanish-American 
war  it  was  used  on  a  large  scale  for  search-lights. 

Mixed  gas  never  was  able  to  hold  a  place  for  general  light- 
ing purposes  in  spite  of  the  stirring  activity  which  many  in- 
vestigators have  shown  in  this  direction.  The  principal  diffi- 
culty is  indeed  in  the  great  danger 
of  explosion,  and  the  difficulty  of  ob- 
taining durable  incandescent  mate- 
rial. Investigation  in  this  direction 
has  not  yet  been  given  up.  For  in- 
stance, there  lies  before  the  author  a 
recently  allowed  Austrian  patent  of 
the  1 5th  of  May,  1901,  to  Urban- 
itzky. 

According  to  this,  the  electrolysis 
of  the  water  takes  place  at  each  lamp 
and  the  mixed  gas  makes  an  incan- 
descent substance  glow.  In  the 
drawing,  shown  in  Fig.  86,  a  b  is  the 
Fig  86  decomposition  vessel,  c  d  the  elec- 

trodes,  ef  the  gas-exit  tubes  which 

end  in  the  double  tube  g,  h  the   glowing  body,  and  i  the 
igniting  device  for  the  mixed  gas. 


SPECIAL  APPLICATIONS. 


121 


Quite  aside  from  the  conditions  and  considerations  of  tech- 
nical operation,  the  patentee  seems  to  have  quite  forgotten 
what  sized  section  of  conductors  he  would  require  to  conduct 
to  each  single  lamp  the  necessary  current  for  the  decom- 
position of  water  at  the  low  tension  of  2.5  to  3  volts. 

(V)    BLASTING  PURPOSES. 

Blasting  purposes.  The  attempts  to  use  mixed  gas  for 
blasting  purposes  are  not  so  generally  known. 

Siemens  &  Halske,  A.  G.,  in  Vienna,  took  up  experiments 
in  1893  to  aPply  electrolysis  directly  to  blasting  purposes. 
The  first  experiment  was  to  produce  haloid  nitrogen  com- 
pounds in  small,  thick  capsules  at  the  place  where  it  was  to 
be  ignited.  Later  the  investigations  were  extended  to  com- 


P  •* 

Utv 


Fig.  87. 


Fig.  88. 


pressed  oxyhydrogen  gas.  The  decomposing  apparatus  were 
thick-walled,  pear-shaped,  glass  flasks  with  two  platinum  wires 
sealed  therein  (Fig.  87). 

These  were  filled  with  the  electrolyte  so  far  that  the  pla- 
tinum wires  were  not  entirely  submerged  and  then  sealed. 
The  ignition  was  produced  after  the  electrolysis  had  been 
finished  by  connecting  the  poles  with  an  induction  coil. 
Larger  experiments  were  made  with  the  apparatus  shown  in 
Fig.  88.  The  affair  was  not  further  investigated  because, 
primarily,  of  difficulties  with  the  patent. 


122 


ELECTROLYSIS  OF   WATER. 


Ochse  tried  to  utilize  the  same  idea.1  He  used  steel  cylin- 
ders, 1 80  mm.  long,  closed  by  a  stopper  which  carries  the 
electrodes  and  the  igniting  apparatus.  These  cylinders  can 
withstand  a  pressure  of  1200  atmospheres  and  contain  22.5 
grams  of  water  and  2.5  grains  of  soda  solution.  Using  8  to 
10  volts  tension,  a  current  strength  of  0.8  to  i  ampere  was 
obtained.  The  electrolysis  was  continued  until  20  grams  of 
water  were  decomposed  and  then  the  explosion  of  the  mixed 
gas  produced  by  an  induction  spark.  The  explosive  power 
of  such  a  cartridge  is  stated  to  be  equivalent  to  150  grams  of 
modern  safety  explosive  containing  ammonium  nitrate  (robu- 
rite,  bellite,  securite,  etc.).  Cornara  has  embodied  the  same  idea 
in  the  English  patent,  302,53  of  the  2ist  of  December,  1897, 
except  that  the  shape  of  the  cartridge  was  somewhat  modified. 
More  recently  it  appears  that  investiga- 
tors have  given  up  the  idea  of  generating 
and  compressing  the  mixed  gas  in  the 
cartridge  itself.  The  attempts  to  use  mixed 
gas  for  blasting  purposes  have  taken  more 
the  direction  of  manufacturing  the  mix- 
ture of  gases  outside  the  cylinder  and  then 
compressing  it  mechanically  into  the  latter. 
As  an  example  of  such  a  cartridge,  we 
illustrate  in  Fig.  89  the  Boehm  filling  ar- 
rangement for  oxy hydrogen-blasting  cart- 
ridges patented  in  Germany  107,531. 
In  this : 

1.  The  cartridge  case. 

2.  The  screwed  in  closing  head. 

3.  The  joint  stopper. 

4.  The  igniting  electrode. 

5.  The  steel  tube  for  filling  the  cartridge  and 
likewise  acting  as  the  second  electrode. 

6.  The  igniting  filament. 

7.  The  screw  attachment  for  fastening  to  the 
air-pump. 

8.  The  screw  for  adjusting  the  valve  stem. 

9.  The  valve  stem. 
TO.     The  cone  joint. 

1  D.  R.  P.,  67153.  Jacobsen,  Repertorium  1893.,  I,  238.  El.  Engineer, 
London,  XXVII,  No.  19,  13  May,  1898.  Electrochem.  Ztschr.,  1898-99., 
127. 


SPECIAL   APPLICATIONS.  123 

We  cannot  so  far  speak  of  the  definite  introduction  of  oxy- 
hydrogen  blasting,  either  by  the  direct  or  indirect  production 
of  the  gases. 

(2)  Hydrogen. 

(a)    BALLOONING  PURPOSES. 

Ballooning:  For  this  purpose  hydrogen  has  been  used 
for  a  long  time,  and  the  electrolytic  production  of  hydrogen 
has  by  far  surpassed  all  other  methods  of  producing  it.  For 
the  purposes  of  ballooning,  the  hydrogen  should  be  as  pure  as 
possible  in  order  that  the  lifting  power  of  the  balloon  may 
be  the  greatest  possible  with  the  smallest  possible  cubical 
content.  By  doing  so,  on  the  one  hand,  expensive  balloon 
material  is  spared ;  on  the  other  hand,  the  cost  of  transporta- 
tion of  the  compressed  gas  is  less.  It  may  be  observed  that 
hydrogen  obtained  in  the  chemical  way  from  iron  and  sul- 
phuric acid  is  nearly  double  as  heavy  as  the  pure  gas  (160  :  89), 
while  electrolytic  hydrogen  can  be  obtained  easily  only  about 
25  per  cent,  heavier  than  the  pure  gas.1  Up  to  the  present, 
the  Italian,  French  and  Swiss  army  bureaus  manufacture  their 
hydrogen  for  balloon  purposes  electrolytically.  The  German 
army  uses  compressed  by-product  hydrogen  from  the  electro- 
lytic alkaline  chloride  plants. 

(£)    SOLDERING  PURPOSES. 

Soldering  purposes :  In  this  line  the  most  prominent 
applications  are  in  the  manufacture  of  accumulators,  and  in 
the  sulphuric  acid  works  for  the  purpose  of  soldering  lead. 

Clean  lead  surfaces,  it  is  well  known,  may  be  easily 
soldered  with  a  blowpipe  with  a  hydrogen-air  flame.  The 
hydrogen  necessary  for  this  was  formerly  exclusively  manu- 
factured by  the  use  of  crude  zinc  and  dilute  sulphuric  acid 
(15  and  20  per  cent).  It  would  lead  us  here  too  far  to  dis- 
cuss the  more  usual  chemical  apparatus  employed  for  evolving 
this  hydrogen  and  so  we  refer  as  far  as  concerns  it  to  the  litera- 
ture of  this  subject.2 

1  W.  Diirer :  Electrochemische  Zeitschr.,  VIII,  2  (1901). 

2  Z.  B.  P.  Schoop:  Die  Sekundarelemente,  II,  41  (1895).     Zeitschr.    f. 
Elektrochemie,  II,  203  (1895-96). 


124  ELECTROLYSIS   OF   WATER. 

One  of  the  principal  disadvantages  of  the  chemical  process 
lies  in  the  circumstance  that  in  dissolving  the  zinc  in  sul- 
phuric acid  the  arsenic  in  the  latter  is  evolved  as  hydrogen 
arsenide  according  to  the  equation 

As2O3  +  6H2SO4  +  6Zn  =  2AsH3  +  3H2O  +  6ZnSO4. 

A  content  of  0.5  per  cent,  of  arsenic  is  not  unfrequently 
found  in  sulphuric  acid  and  it  is,  therefore,  easily  seen 
that  constant  working  under  such  conditions  with  hydro- 
gen generators,  which  are  often  not  perfectly  tight  and  there- 
by allow  unburned  gas  to  escape  from  burners  which  are 
extinguished  but  not  entirely  turned  off,  results  in  the  most 
disagreeable  sanitary  consequences  for  the  workmen.  For 
this  reason  the  accumulator  constructors  themselves  have  pro- 
posed to  pass  this  chemically  prepared  hydrogen  through  red 
hot  copper  tubes  and  afterwards  to  cool  it,  by  which  operation 
the  arsenic  is  seperated  out,  or  the  gas  is  freed  from  arsenic 
by  washing  with  potassium  permanganate  solution.1 

These  sanitary  difficulties  are  naturally  completely  avoided 
by  the  use  of  electrolytic  hydrogen.  Also  the  danger  of  ex- 
plosion in  the  apparatus  itself  is  less  with  this  manner  of 
manufacture.  Finally  when  using  electrolytic  hydrogen  gen- 
erators, the  oxygen  simultaneously  generated  can  be  used  in 
place  of  air  in  the  blast-flame,  which  results  in  a  saving  of 
about  50  per  cent,  of  the  time  necessary  for  soldering. 

Also  from  the  point  of  view  of  economy  the  electrolytic 
method  of  manufacture  has  the  advantage  over  the  chemical. 

For  i  kilogram  of  zinc  costing,  to-day,  8^  cents,  2  kilo- 
grams of  sulphuric  acid  are  required,  costing  3)^  cents.  For 
this  outlay  of  12  ^  cents  there  is  theoretically  only  32  grams 
or  not  quite  360  litres  of  hydrogen  to  be  obtained.  Since  the 
zinc  and  acid  are  not  completely  used  up,  it  may  be  assumed 
that  800  ampere-hours  would  electrolytically  produce  an  equal 
volume  of  hydrogen.  Using  2.5  volts  working  tension,  2 
kilowatt  hours  would  be  necessary,  which,  at  the  price  of 

1  P.  Schoop  :  Die  Sekundarelemente,  II,  45,  (1895). 


SPECIAL   APPLICATIONS.  125 

power  already  assumed — ^  to  i  J^  cents, would  cost  y2  to  2j4 
cents. 

The  total  costs  for  the  soldering  have  been  determined  by 
the  results  of  operation  in  various  accumulator  factories  to  be 
about  one-half  cheaper  with  the  electrolytic  apparatus  than 
with  the  chemically  generated  hydrogen.  Besides  the  econ- 
omy in  the  cost  of  gas  and  time,  there  can  also  be  taken  into 
consideration  the  diminution  of  the  labor  required. 

The  gas  must  naturally  be  compressed  for  use  outside,  yet 
the  weights  to  be  transported  in  gas  flasks  are  no  greater  in 
the  one  case  than  in  the  other. 

M.  U.  Schoop  has  recently  published  an  interesting  disser- 
tation on  the  soldering  of  lead  with  compressed  oxygen  and 
hydrogen.1  Since  this,  however,  does  not  include  the  electro- 
lytic production  of  the  gases,  but  only  their  use  after  being 
compressed  and  their  extensive  applications  in  this  direction, 
we  refer  to  the  original  paper. 

It  may  be,  however,  mentioned  that  since  the  soldering 
flame  must  have  reducing  qualities,  when  electrolytically  pro- 
duced gas  is  used,  there  is  a  certain  excess  of  unused  oxygen. 
The  gases  are  consumed  in  the  proportion  of  i  hydrogen  to 
j£  oxygen  instead  of  i  hydrogen  to  y2  oxygen  as  furnished 
by  the  electrolyzers. 

Soldering  with  the  soldering  iron  and  easily  fusible  solder 
often  competes  with  the  hydrogen  soldering,  yet  according 
to  the  reports  of  professional  people  a  cleaner  lead  surface  is 
necessary  and  the  quality  of  the  soldered  joint  is  not  equal  to 
that  produced  by  the  autogenous  soldering  of  the  lead,  quite 
aside  from  the  considerations  of  the  sanitary  inconveniences 
resulting  from  the  content  of  mercury  in  the  easily  fusible 
solder. 

In  the  sulphuric  acid  industry  the  hydrogen  soldering  with 
electrolytically  generated  gas  is  of  particular  importance  be- 
cause of  the  quick  soldering  of  vertical  seams. 

Heraeus  in  Hanau  has  used  with  good  success  the  blast- 
flame  with  a  large  excess  of  hydrogen  for  the  autogenous 

1  Zeitschr.  f.  Elektrotechnik,  Wien,  XIX  224,  (1901). 


126  ELECTROLYSIS   OF  WATER. 

soldering  of  aluminium.     The  samples  of  work  shown  at  the 
Paris  Exposition  attracted  considerable  attention. 

(V)    LIGHTING. 

Lighting:  The  attempts  for  using  hydrogen  for  the 
purposes  of  lighting  go  back  to  the  year  1846  when  Gillard, 
in  France,  introduced  a  process  by  which  a  little  basket  of 
platinum  wire  was  brought  to  a  white  heat  by  burning  hydro- 
gen. A  successful  result  was  not  obtained,  as  was  also  the 
result  of  attempts  of  White  and  Leprince  to  use  carburized 
hydrogen.  More  recently  Schmidt  has  taken  up  the  applica- 
tion of  hydrogen  for  lighting  purposes  in  combination  with 
the  Auer  (Welsbach)  mantle. 

Schmidt  first  presented  his  views  upon  this  subject  before 
the  Seventh  Yearly  Assembly  of  the  German  Electrochemical 
Society  in  Zurich,  in  1900,  and  a  lively  debate  arose  on  the 
subject,  in  which  especially  Nernst  brought  out  the  high  re- 
quirements of  the  mantles  for  the  use  of  hydrogen  gas,  and 
Forster  the  difficult  question  of  suitable  stop-cocks. 

Concerning  the  views  of  Schmidt  he  has  most  accurately 
expressed  them  to  the  author  in  a  long  private  communication, 
the  most  important  of  them  being  here  reproduced  in  abstract : 

The  most  advantageous  qualities  of  hydrogen  which  appear 
to  make  it  well  suited  for  lighting  purposes  are  its  harmless- 
ness  for  the  human  organs  and  high  heat  of  combustion,  the 
small  weight,  the  relatively  high  ignition  point,  the  easy 
conductibility,  and  the  chemical  inactivity  of  the  same  towards 
the  fittings.  Its  combustion  produces  only  water  vapor,  no 
foul  smelling  products,  and  it  takes  from  the  atmosphere  the 
smallest  amount  of  oxygen.  The  flame  is  really  non-luminous 
but  will  heat  a  Welsbach  mantle  to  the  brightest,  white 
heat,  whereby  a  mantle  of  ordinary  size  will  give  a  far  too 
great  amount  of  light  (several  hundred  candle-power)  for  or- 
dinary purposes. 

Schmidt  uses,  therefore,  in  his  light  investigations,  a  very 
much  smaller  mantle,  about  6  cm.  long  and  0.5  cm.  in 
diameter,  one  of  which  is  shown  in  Fig.  90.  The  smaller  di- 


SPECIAL   APPLICATIONS. 


I27 


mensions  makes  the  mantle  more  proof  against  damage  by 
vibrations. 

The  difficulties  named  by  Nernst  of  the  greater  require- 
ments of  a  mantle  for  withstand- 
ing the  hydrogen  flame  are,  ac- 
cording to  the  view  of  Schmidt, 
balanced  by  the  circumstances 
that  the  hydrogen  contains  no  im- 
purities, as  iron  compounds  and 
dust  which  in  other  cases  affect 
the  durability  of  the  mantles.  The 
inconvenient  quality  of  being 
without  odor  is  shared  by  both 
hydrogen  and  water-gas,  and  this 
difficulty  in  the  use  of  the  gas  for 
lighting  can  be  overcome  in  the 
case  of  hydrogen  in  the  same  way 
it  is  managed  with  water,  i.  e.,  by 
introducing  into  it  small  quanti- 
tities  of  mercaptan  vapor. 

A  very  small  amount  of  hydro- 
gen gas  needs  to  be  used  on  ac- 
count of  its  high  temperature  of  combustion. 

Schmidt  compares  in  his  experiments  hydrogen  with  illu- 
minating gas  and  acetylene,  and  believes  the  superiority  of 
the  first  to  be  proven  by  the  following  facts : 

(1)  Sanitary  advantage,  since  only  water  vapor  results  as  a 
product  of  combustion  and  the  minimum  amount  of  oxygen 
is  withdrawn  from  the  atmosphere  with  a  much  less  develop- 
ment of  heat. 

(2)  A  very  much  smaller  section  of  piping  required.     These 
are  for  hydrogen,  used  at  a  similar  pressure  and  volume,  one- 
eighth  the  size  necessary  for  illuminating  gas  and  one-tenth 
that  for  acetylene.     Referred  to  the  candle-power  developed, 
the  sizes  of  piping  necessary  for  hydrogen  is  only  one-fifteenth 
and  one-ninth  that  needed  for  the  other  gases. 


Fig.  90.— Burner  for  hydrogen  light. 


128  ELECTROLYSIS   OF   WATER. 

(3).  Very  much  easier  and  less  dangerous  compressibility  to 
many  hundred  atmospheres  without  altering  the  qualities  of 
the  gas,  while  illuminating  gas  is  rendered  valueless  by  com- 
pression, the  oil  and  fat  gas  used  for  lighting  cars  can  be 
compressed  only  to  10  atmospheres  and  acetylene  cannot  be 
compressed  higher  than  2  atmospheres  on  account  of  the  dan- 
ger of  explosions. 

(4).  The  possibility  of  higher  pressures  in  the  gas  pipes,  so 
that  the  flame  may  be  turned  in  any  direction,  even  down- 
wards, which  is  practicable  with  a  pressure  of  200  mm.  of 
water. 

(5).  Smaller  dangers  of  explosions  since  the  latter  can  only 
take  place  when  it  contains  9.5  per  cent,  of  air,  on  the  con- 
trary with  acetylene  when  it  contains  3.8  per  cent.,  with  illu- 
minating gas  8  per  cent. ;  since  the  difTusibility  of  hydrogen  is 
twenty  times  greater  than  that  of  air  the  mixing  of  the  gas 
with  the  air  takes  place  much  more  rapidly. 

Concerning  the  cost  of  lighting  with  hydrogen,  Schmidt 
gives  the  following  comparative  figures  for  the  above  men- 
tioned kinds  of  gas. 

Using  illuminating  gas  with  a  heat  value  of  5000  calories 
when  burned  in  a  Welsbach  burner,  there  is  used  per  normal 
candle-power  hour  2.1  litres,  if  used  at  220  mm.  pressure  i 
litre,  with  hydrogen  somewhat  less  than  i  litre,  with  acetylene 
0.75  litre,  and  with  the  proposed  but  not  yet  achieved  com- 
bustion of  the  latter  in  the  Welsbach  mantle  0.36  litre. 

Since  the  consumption  of  gas  varies  naturally  with  the 
strength  of  the  flame,  Schmidt  found  the  consumption  of 
hydrogen  per  candle-power  hour  to  be  in  small  burners  1.5 
litres  for  each  burner,  for  large  burners  i  litre,  and  as  an 
average  1.25  litres. 

With  reference  to  their  production  by  means  of  electricity, 
the  present  values  between  the  hydrogen  light  and  the  calcium 
carbide,  that  is,  acetylene,  is  to  the  advantage  of  the  former. 
One  kilowatt  day  produces  4  cubic  metres  of  hydrogen  and 
equals  3200  candle-power  hours  on  the  one  hand,  and  4  kilo- 


SPECIAL   APPLICATIONS.  1 29 

grams  of  calcium  carbide  equivalent  to  1200  litres  of  acetylene 
or  1600  candle-power  hours  on  the  other.  In  this  pre- 
sentation, however,  the  very  much  greater  consumption  of 
raw  materials  and  electrodes  in  the  production  of  calcium 
carbide  in  comparison  with  the  electrolysis  of  water  has  not 
been  taken  into  account.  In  order  to  attain  a  more  exact 
basis  of  comparison,  Schmidt  starts  with  the  market  price  of 
calcium  carbide  and  calculates  the  same  as  6%  cents  per 
kilogram,  the  cost  production  being  3.625  cents.  Out  of  the 
latter  figures,  1.25  cents  is  referable  to  raw  materials  and  its 
preparation  so  that  2.375  cents  remains  for  current,  furnacing, 
and  general  expenses.  If  the  current  is  reckoned  at  one  cent, 
there  remains  for  the  power  only  0.165  cent  kilowatt  hour,  a 
price  only  possible  in  very  large  plants. 

Assuming  a  cost  price  of  3.625  cents  per  kilogram  of  car- 
bide from  which  4oo-candle-power  is  obtainable,  there  could 
be  obtained  electrolytic  hydrogen  to  a  volume  of  1540  litres 
or  1230  candle-power  hours. 

As  against  this  better  utilization  of  power  in  the  manufac- 
ture of  hydrogen  must,  however,  be  placed  the  easier  storage 
and  carriage  of  calcium  carbide.  Schmidt  makes  the  follow- 
ing comparisons  with  reference  to  the  consumption  of  power 
for  the  compression  of  hydrogen,  freight  costs  for  transporta- 
tion and  return  of  the  flasks  (10  kilograms  per  cubic  metre), 
and  sinking  fund  on  the  assumption  of  twenty  shipments 
per  year. 

The  cost  of  10,000  candle-power  hours  transported  500  kilo- 
metres (300  miles) : 

From  carbide.  From  hydrogen. 

26  kg.  of  carbide $  .90  12.5  cubic  metres  of  hydrogen  $  .295 

Packing .10  Compression .025 

Evolution  of  acetylene,  purifica-  Interest  on  flasks .1625 

tipn  and  interest  on  apparatus  .10          Emptying  and  adjusting  valves  .0200 

Freight  300  miles .125         Freight    and    return    for  300 

miles 6250 

$1-225 

$1-1275 

It  is  seen  from  this  comparison   that  the  distance  of  300 


130  ELECTROLYSIS   OF   WATER. 

miles  is  about  the  limit  at  which  hydrogen  can  compete  with 
acetylene. 

For  small  distances,  distribution  in  pipes  would  naturally 
be  used.  What  difficulties  would  in  that  case  be  encountered 
in  preserving  the  tubes  gas-tight  cannot  be  necessarily  fore- 
told from  an  experimental  study  of  the  subject. 

(d)    MOTOR  PURPOSES. 

Motor  purposes :  The  evident  applicability  of  hydrogen 
for  motor  purposes  has  likewise  been  often  taken  into  con- 
sideration, but  at  the  present  no  results  worth  mentioning 
have  been  obtained. 

(3)  Oxygen. 

Concerning,  finally,  the  application  of  oxygen  there  is  no 
question  that  with  a  sufficiently  low  price,  quite  a  number  of 
extended  applications  would  be  found.  The  hastening  of 
oxidation  processes  and  intensifying  of  combustion  is  in  many 
cases  the  end  which  is  being  actively  sought  after.  In  many 
steel  works,  electrolytic  oxygen  is  at  present  being  experi- 
mentally used  in  place  of  air  in  the  Bessemer  converter. 
Even  in  various  blast-furnace  processes  the  application  of 
oxygen  has  been  thought  of  if  the  difficulties  could  be  over- 
come in  finding  a  suitable  material  for  constructing  the  fur- 
nace. 

Investigations  in  the  glass  industry  have  shown  that  the 
introduction  of  oxygen  into  the  fluid  mass  of  glass  results  in 
an  economy  of  40  to  50  per  cent,  in  labor,  time,  fuel  and  de- 
terioration, without  damaging  the  quality  of  the  glass.  The 
extensive  application  of  oxygen  in  the  manufacture  of  sul- 
phuric acid  according  to  the  contact  process  is  indeed  only  a 
question  of  time. 

In  organic  technology,  oxygen  is  already  used  for  many 
purposes.  It  is  used,  for  instance,  partly  as  ozone  for  the 
ageing  of  alcoholic  beverage,  in  the  manufacture  of  varnishes, 
and  in  the  purification  of  illuminating  gas.  More  recently 
oxygen  has  been  used  in  the  preservation  of  milk,  the  freshly 


SPECIAL  APPLICATIONS.  131 

obtained  milk  being  saturated  with  oxygen  at  a  pressure  of  5 
to  6  atmospheres  and  allowed  to  stand  several  hours  under 
this  pressure.  After  diminishing  the  pressure  to  two  atmos- 
pheres, the  milk  is  ready  for  transportation. 

In  the  production  of  ozone,  oxygen  would  be  used  in  all 
those  cases  in  place  of  air,  in  which  the  introduction  of  nitro- 
gen compounds  into  the  product  treated  with  ozone  is  to  be 
avoided. 

Finally  compressed  oxygen  has  manifold  uses  in  medicine 
and  hygiene,  and  in  particular  for  the  improvement  of  the 
air  in  rooms  where  renewal  of  the  air  is  not  possible,  also  for 
instance  in  mines  and  at  fires  or  under  such  conditions  where 
very  attenuated  air  makes  breathing  difficult,  as  in  balloon 
ascensions. 

It  would  surpass  the  limits  of  this  volume  to  go  into  the 
methods  of  analysis  -of  the  gases  of  which  we  have  treated, 
and  concerning  this  subject  we  refer  to  the  numerous  special 
treatises.1 

There  remains  only  to  the  author  the  agreeable  duty  to 
thank  most  heartily  Messrs.  Dr.  Hammerschmidt,  of  Niirn- 
berg,  Dr.  Schmidt,  of  Zurich,  and  M.  U.  Schoop,  of  Cologne, 
for  the  furnishing  of  original  material,  and  also  Dr.  Abel,  of 
Vienna,  for  friendly  help  in  the  reading  of  the  proof. 

1  Bunsen  :  Gasometrische  Methoden.  W.  Hempel :  Gasanalytische  Me- 
thoden,  II  Auflage,  1890.  Cl.  Winkler :  Lehrbuch  der  technischen  Gas- 
analyse,  III  Auflage,  1901:  B.  Neumann:  Gasanalyse  und  Gasvolumetrie, 
1901. 


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as 


TABLE  XIV. 

TENSION  OF  WATER  VAPOR  IN  MM.  OF  MERCURY  FOR  TEMPERATURES  BE- 
TWEEN —2°  C.  to  +35°  C. 

(From  Regnault's  Messungen  berechnet  von  Broch,  see  Trav.  et  Mem.  du 
Bur.  intern,  des  Poids  et  Mes.  I.  A.  page  33,  1881.) 


°c. 

Ten- 
sion, 
mm. 

°c. 

Ten- 
sion, 
mm. 

°c. 

Ten- 
sion, 
mm. 

°C. 

Ten- 
sion, 
mm. 

°c. 

Ten- 
sion, 
mm. 

—2.0 

3-950 

+  i-7 

5.161 

+5.3 

6.643 

+  9-° 

8.548 

+12.7 

10.921 

•9 

3-979 

1.8 

5.198 

5-4 

6.689 

9-i 

8.606 

12.8 

10.993 

.8 

4.008 

+  1.9 

5-235 

5-5 

6.736 

9-2 

8.664 

+  12.9 

11.065 

•7 

4.038 

5-6 

6.782 

9-3 

8.722 

.6 

4.067 

+  2.0 

5.272 

5-7 

6.829 

9-4 

8.781 

+  I3-0 

H-I37 

•  5 

4.097 

2.1 

5.309 

5-8 

6.876 

9-5 

8.840 

I3-1 

II.2IO 

•  4 

4.127 

2.2 

5-347 

+5-9 

6.924 

9-6 

8.899 

13.2 

11.283 

•  3 

4-157 

2-3 

5.385 

9-7 

8-959 

13.3 

II   356 

.2 

4.188 

2.4 

5-424 

+6.0 

6.971 

9.8 

9.019 

13.4 

11.430 

r 

4.218 

2.5 

5.462 

6.1 

7.O2O 

+  9-9 

9.079 

13.5 

II.505 

2.6 

5-501 

6.2 

7.068 

13.6 

11.580 

—  1.0 

4.249 

2-7 

5-540 

6.3 

7.II7 

+  10  0 

9-140 

13.7 

H.655 

0.9 

4.280 

2.8 

5-579 

6.4 

7.166 

10.  1 

9.201 

13.8 

11.731 

0.8 

4-312 

+2.9 

5.618 

6-5 

7-215 

10.2 

9.262 

+13.9 

11.807 

0.7 

4-343 

6.6 

7.265 

10.3 

9.324 

0.6 

4-375 

+3.0 

5.658 

6.7 

7-314 

10.4 

9.386 

+14.0 

11.884 

0.5 

4.406 

3.1 

5.698 

6.8 

7o65 

10.5 

9-449 

14.1 

11.960 

0.4 

4.438 

3.2 

5.738 

+6.9 

7.415 

10.6 

9-512 

14.2 

12.038 

0-3 

4.471 

3.3 

5-779 

10.7 

9-575 

14.3 

12.116 

0.2 

4.503 

3.4 

5-820 

+  7-0 

7.466 

10.8 

9.639 

14.4 

12.194 

—O.I 

4.536 

3.5 

5.860 

7.1 

7.517 

+10.9 

9-703 

14.5 

12.273 

3.6 

5.902 

7.2 

7-568 

14.6 

12.352 

0.0 

4.569 

3-7 

5.943 

7-3 

7.620 

+  11.  0 

9-767 

14.7 

12.432 

+0.1 

4.602 

3-8 

5.985 

7.4 

7.672 

ii.  i 

9.832 

14.8 

12.512 

0.2 

4.635 

+3-9 

6.027 

7-5 

7-725 

II.  2 

9.897 

+14.9 

12.593 

0-3 

4.668 

7-6 

7-777 

H.3 

9.962 

0.4 

4.702 

+4.0 

6.069 

7-7 

7.830 

II.4 

10.028 

+15.0 

12.674 

0-5 

4.736 

4.1 

6.  112 

7.8 

7-883 

II.5 

10.095 

15.1 

12.755 

0.6 

4.770 

4.2 

6.155 

+7-9 

7-937 

u.6 

10.161 

15.2 

12.837 

0.7 

4-805 

4-3 

6.198 

ii.  7 

10.228 

J5-3 

12.920 

0.8 

4.839 

4.4 

6.241 

+8.0 

7.991 

ii.  8 

10.296 

15.4 

13.003 

+0.9 

4.874 

4-5 

6.285 

8.1 

8.045 

+  11.  9 

10.364 

15-5 

13.086 

4.6 

6.328 

8.2 

8.100 

15-6 

13.170 

+1.0 

4.909 

4.7 

6.373 

8-3 

8.155 

+  12.  0 

10.432 

15-7 

13-254 

i.i 

4-944 

4-8 

6.417 

8.4 

8.210 

12.  1 

10.501 

15-8 

13-339 

1.2 

4.980 

+4-9 

6.462 

8.5 

8.266 

12.2 

10.570 

4-^5-9 

13-424 

i-3 

5.016 

8.6 

8.321 

12.3 

10.639 

1.4 

5-052 

+5-0 

6.507 

8.7 

8.378 

12.4 

10.709 

+  16.0 

13-510 

1.5 

5.088 

5-1 

6.552 

8.8 

8.434 

12-5 

10.780 

16.1 

13-596 

+  r.6 

5-124' 

+5-2 

6.597 

+8.9 

8.491 

+  12.6 

10.850 

+  16.2 

13-683 

TABLE  XIV.— (Continued.} 


°c. 

Ten- 
sion, 
mm. 

°c. 

Ten- 
sion, 
mm. 

°c. 

Ten- 
sion, 
mm. 

°c. 

Ten- 
sion, 
mm. 

°c. 

Ten- 
sion, 
n 

+16.3 

I3-770: 

+  20.1 

17.471 

+23.8 

21.888 

+27.5 

27.258 

+31-2 

33-749 

16.4 

13.858 

20.2 

17-579 

+23-9 

22.O2O 

27.6 

27.418 

31-3 

33-942 

16.5 

I3-946 

20.3 

17.688 

27.7 

27.578 

3i.4 

34-136 

16.6 

14.035 

20.4 

17-797 

+24.0 

22.152 

27.8 

27.740 

3i-5 

34.330 

16.7 

14.124 

20.5 

17.907 

24.1 

22.286 

+27.9 

27.902 

31.6 

34.526 

16.8 

14.2141 

20.  6 

18.018 

24.2 

22.420 

31-7 

34.722 

+  16.9 

14-304  ; 

20.7 

18.129 

24-3 

22-554 

31-8 

34.920 

20.8 

18.241 

24-4 

22.690 

+28.0 

28.065 

+3r-9 

35-119 

+17.0 

14-395 

+  2O.Q 

18.353 

24.5 

22.826 

28.1 

28.229 

17.1 

14.486- 

24.6 

22.963 

28.2 

28.394 

17.2 

14.5/81 

24-7 

23.100 

28.3 

28.560 

+32.0 

35.318 

17-3 

14.670  ! 

+  21.0 

18.466 

24.8 

23.239 

28.4 

28.726 

32.1 

35-5I9 

17.4 

14-763 

21.  1 

18.580 

+24-9 

23.378 

28.5 

28.894 

32.2 

35-720 

17-5 

14.8561 

21.2 

18.694 

28.6 

29.062 

32-3 

35-923 

17.6 

14-950 

21.3 

18.808 

28.7 

29.231 

32-4 

36.126 

17-7 

15.044 

21.4 

18.924 

+25-0 

23.517 

28.8 

29.401 

32.5 

36.331 

17.8 

15.136 

21-5 

19.040 

25-1 

23-658 

+28.9 

29-572 

32.6 

36.536 

+17-9 

15-234 

21.6 

19.157 

25.2 

23.799 

32.7 

36.743 

21.7 

19.274 

25.3 

23.941 

+29.0 

29-744 

32.8 

36.950 

+  18.0 

15-330 

21.8 

19.392 

25-4 

24.084 

29.1 

29.916 

+32.9 

37.159 

18.1 

15-427 

+21.9 

19.510 

25.5 

24.227 

29.2 

30.090 

18.2 

15-524 

25.6 

24.371 

29.3 

30.264 

+33-0 

37-369 

18.3 

15.621 

+  22.0 

19.630 

25-7 

24.516 

29.4 

30.440 

33-  i 

37.580 

18.4 

J5-7I9 

22.1 

I9.750 

25-8 

24.662 

29.5 

30.616 

33-2 

37.791 

18.5 

15.818 

22.2 

19.870 

+25-9 

24.808 

29.6 

30.793 

33-3 

38.004 

18.6 

I5.9I7 

22.3 

19.991 

29.7 

30.971 

33-4 

38.218 

18.7 

16.017 

22.4 

2O.II3 

+26.0 

24.956 

29.8 

3I-I49 

33-5 

38.433 

18.8 

16.117 

22.5 

20.236 

26.1 

25.104 

+29.9 

3I-329 

33-6 

38.649 

+  18.9 

16.218 

22.6 

20-359 

26.2 

25.252 

33-7 

38.866 

22.7 

20.482 

26.3 

25.402 

+30.0 

31-510 

33-8 

39.084 

+19.0 

16.319 

22.8 

20.607 

26.4 

25.552 

30.1 

31.691 

+33-9 

39.303 

19.1 

16.421 

+  22.9 

20.732 

26.5 

25.703 

30.2 

3L873 

19.2 

16.523 

26.6 

25.855 

30.3 

32.057 

+34-0 

39.523 

J9-3 

16.626 

26.7 

26.008 

30.4 

32.241 

34-1 

39-744 

19.4 

16.730 

+23.0 

20.858 

26.8 

26.l6l 

30.5 

32.426 

34.2 

39.966 

19-5 

16.834 

23.1 

20.984 

+26.9 

26.316 

30.6 

32.612 

34-3 

40.190 

19.6 

16.939 

23.2 

21.  Ill 

30.7 

32.800 

34-4 

40.414 

19.7 
19.8 

17.044 
17.150 

23.3 
234 

21.239 
21.367 

+27.0 
27.2 

26.470 
26.626 

30.8 
+30.9 

32.988 
33.176 

34-5 
34-^ 

40.640 
40.866 

+  19-9 

17-256 

23.5 

21.496 

27.2 

26.783 

34-7 

41.094 

23-6 

21.626 

27-3 

26.940 

+31.0 

33.366 

34-8 

4i-323 

+20.0 

17.363 

+23-7 

21.757 

+27-4 

27.099 

+31.1 

33-557 

H-34-9 

4L553 

TABLE  XV. 
CONDUCTIVITY  OF  THE  ELECTROLYTES  WHICH  ARE  MADE  USE  OF  IN  THE 

TECHNICAL  ELECTROLYSIS  OF  WATER. 
The  table  is  for  the  temperatures  of  the  solutions  of  18°  C. 
P  =  Percentage  by  weight  of  the  anhydrous  electrolyte  in  100  parts  of  the 

solution. 

t\  =  Number  of  gram-equivalents  in  i  cc.  of  the  solution  ;  in  the  calcula- 
tion of  the  gram-equivalents  and  litres  m  —  1000,  n  =  the  concentra- 

tion, or  v  =  —  the  dilution. 
m 

s  =  Specific  gravity  of  the  solution  between  15°  and  18°  referred  to  water 
at  4°  C. 

XK  —  Conductivity  in—  at  18°  C. 


The  temperature  coefficient  gives  in  terms  of  x^  the  alteration  of  x  for  +1°, 
and  indicates  the  mean  change  between  18°  and  26°. 
Interpolated  values  are  enclosed  in  brackets. 


Electrolyte. 

p. 

IOOO  TJ 

stk. 

10*  XW. 

(m;  ilv) 

"i18   V    <f7/22 

% 

g-Eq.  in  1. 

t=  18° 

Na2C03 

5 

0.991 

1.0511 

451 

0.0252 

10 

2.082 

1.1044 

705 

0.0271 

15 

3-277 

1.1590 

836 

0.0294 

K2C03 

5 

0.756 

1.0499 

561 

O.O22I 

10 

1-579 

1.0919 

1038 

O.O2I2 

20 

3-448 

1.1920 

1806 

O.O2IO 

30 

5.641 

1.3002 

2222 

O.O2I9 

40 

8.198 

1.4170 

2168 

O.O246 

50 

H.I57 

1.5428 

1469 

0.0318 

/=  18° 

H2S04 

5 

1-053 

.0331 

2085 

O.OI2I 

10 

2.176 

.0673 

39  i  5 

O.OI28 

15 

3-376 

.1036 

5432 

0.0136 

20 

4.655 

.1414 

6527 

0.0145 

25 

6.019 

.1807 

7171 

0.0154 

30 

7.468 

.2207 

7388 

0.0162 

35 

9.011 

.2625 

7243 

O.OI7O 

40 

10.649 

•3056 

6800 

0.0178 

(45) 

12.396 

.3508 

6146 

0.0186 

50 
(55) 

14-258 
16.248 

3984 
.4487 

5405 
4576 

0.0193 
0.0201 

60 

18.375 

•5019 

3726 

0.0213 

65 

20.177 

-5577 

2905 

O.O23O 

70 

23.047 

.6146 

2157 

0.0256 

i  Taken  from  Kohlrausch  and   Holborn, 
Teubner.  Leipzig. 


Das   Leitvermogen  der    Elektrolyte,    1898. 


TABLE  XV—  ( Continued. ) 


Electrolyte. 

P. 

looo  r) 
(m  ;  I/T/) 

„, 

„,, 

-     (-*-  } 

X-H    \    (It     /S2 

% 

g-Eq.  in  1. 

/=  18° 

H,SO4 

75 

25-592 

.6734 

1522 

O.O29I 

80 

28.25 

.7320 

1105 

0.0349 

85 

30.90 

.7827 

980 

0.0365 

90 

33-34 

.8167 

1075 

0.0320 

95 

35.58 

.8368 

1025 

O.0279 

NaOH 

2-5 

0.641 

(  .0280) 

jo87 

1 
O.OI94 

5 

I«3I9 

.0568 

1969 

O.02OI 

10 

2.779 

.1131 

3I24 

0.0217 

(15) 

4-381 

.1700 

3463 

0.0249 

20 

6.122 

.2262 

"$270 

O.0299 

(25) 

8.002 

.282;, 

2717 

0.0368 

3° 

10.015 

•3374 

20^2 

0.0450 

(35) 

12.150 

•39°7 

1507 

0.0551 

40 

14.400 

.4421 

1  164 

0.0648 

42 

15.323 

.4615 

1065 

0.0691 

KOH 

4.2 

0.777 

.0382 

1464 

O.OI87 

8.4 

1.612 

.0776 

•  2723 

0.0186 

(12.6) 

2.508 

.1177 

3763 

0.0188 

16.8 

3-467 

.1588 

4558 

0.0193 

(21.0) 

4.491 

.2008 

5106 

0.0199 

25.2 

5.583 

.24^9 

5403 

0.0209 

(29-4) 

6.744 

1.2880 

5434 

0.0221 

33-6 

7.978 

•3332 

5221 

0.0236 

(37.8) 

9.292 

.^802 

4790 

0.0257 

42.0 

10.695 

1.4298 

4212 

0.0283 

Author's  Index* 


A.                        Coehn  105  —  108 

Gautherot  4 

Connell  5 
Alemani  4 

Geissler  &  Co.  46 

,                                           Cornara  122 
Anderson  5 
Crova  3,  5 
Andrews  5 

Ascherl  49,   108,   119            Cruikshank  4 

Gerland  6 
Geuther  5 
Gilbert  4 
Gillard   126 

D. 

Gladstone  6,  48 

. 

D'Arsonval  10,   u,    108 

G  laser  8 

Bassani  74,  ?8                        D 

Graham  6,  48 

Bell  24,  26,  108                    Ddi-nii  I 

Gren   i 

Becquerel  4,  6                       De  ]a  Metherie  I 

Grotthus  4 

Berggewerkschaftl.  Lab-     De  Ja  Rivg  ^   4    ^  Q2 

Grove  4 

oratorium  Bochum  31 

Delmard  23,  108 

Berthelot  6 

Del  Proposto  63,  71 

H. 

Bertin  97 
Blanc  6 
Blum  102,  108 
Boehm  122 
Bonijol  4 
Borchers  78 

Despretz  5 
Drummond  120 
Ducretet  19—23,   108 
Diirer  123 
Dumas  5 

Haber   1  13 
Habermann  48,   106  —  108 
Hammerschmidt  86 
Hartmann  &  Braun  91 
Hazard-Flamand  58,  108 

Bossi  78 

E. 

Helmholtz  7 

Bourgoin  5 

Heraeus  88,  112,  125 

Branville  &  Cie.   10 

Elbs  93 

Hess  86 

Breda  5 

Eldridge  102,   108 

Hittorf  6 

Brewster  3,  5 

Exner  6 

H  offer  107 

Brunner  3,  5 

F 

Hofmann  5,  45,  47 

Buff  5,  46 

X  » 

Hoppe  2 

Buffa  63,  72,  74,  75 

Faraday  7 

Bunsen  92  —  93 

Foerster  126 

J. 

Fonvielle  5 

c. 

Foucault  5 

Jacobi  4 

Callau  5 

Friedel  5 

Jamin  3—4 

Carlisle  2 

K. 

Caspar!  8 

• 

Claire-Deville  119 

Garuti  52,  61  —  63,  67  —  83, 

Kard  4 

Clarke  102,   108 

108,  in  —  113 

Klingert  4 

140 


Kolner    Accumulatoren- 

werke  G.  Hagen  57 
Kohlrausch  8,  91 
Kopp  i,  2 

L. 

Landriana  3 

Latchinoff    n  —  18,    30, 

108 

Leblanc  4,  6 
Le  Blanc  7 
Leprince  126 
Linde  116 — 117 
L'Oxyhydrique  francaise 

76 

M. 

Maschinenfabrik     Oerli- 

kon  42 
Millon  4 
Minet  98 — 100 
Murray  4 

N. 

Naber  89 
Nernst  126 — 127 
Neumann  95 
Nicholson  2 — 4 

0. 

Obach  80— 81,  108,  in— 

"3 

Ochse"  122 
Osann  3,  5 
X)stwald  i — 2,  43 


P. 

|  Pacts  van  Troostwijk  i,  4 
Pearson  4 
Pfaff  4 

Pompili  63,  69,  80,  108 
Pouillet  4 

R. 

Rebenstorff  47 

Renard  10,  19 — 24,  108 — 

in 

Ritter  i — 2,  43 
Rosenfeld  46 
Rundspaden  6 

s. 

Sauerstoff-  und  Wasser- 

stoffwerke  Luzern   31, 

76 
Schmidt  27—33,  39,    42, 

55,   72—73,    1 08,  1 10— 

113,  127 — 128 
Schoene  6 
Schoenherr  93 
Schoop,  M.  U.  52—58, 

76,  108,  in,  113,  118, 

125 

Schoop,  P.  124 
Schuckert  &  Cie.  52,  83, 

86—88,  108,  in— 112 
Schiitz  78 

Schumacher-Kopp  31 
Shepard  5 
Siemens  Brothers  &  Cie. 

80 — 81,  108,  in — 113 


Siemens  &  Halske  A.-G. 

121 

Simon  4 

Societe"  anonyme  1'Oxy- 

hydrique  69,  76,  108 
Socie"te  de  Montbard  76 
Sorel  5 
Sorets,  46 
Stormer  115 
Sylvester  4 

T. 

Tacker  89 
Thirion  78 
Thomson  7 
Tribe  49 

U. 

Urbanitzky  120 

V. 

Vereinigte       Chemische 
FabrikenxLeopoldshall 

i'5 

Verney  61,  108 
Vigau  4 
Voigt  2,  43 
Volta  i—2 

w. 

Walter  95 
Weber  4 
White  126 
Wilkinson  4 
Winssinger  74 
Wollaston  4 


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